Molecular Microbiology最新文献_第6页

Dissecting the role of the MS‐ring protein FliF in Bacillus cereus flagella‐related functions 剖析 MS 环蛋白 FliF 在蜡样芽孢杆菌鞭毛相关功能中的作用

IF 3.6 2区生物学

Molecular Microbiology Pub Date : 2024-07-19 DOI: 10.1111/mmi.15299

Diletta Mazzantini, Guendalina Gherardini, Virginia Rossi, Francesco Celandroni, Marco Calvigioni, Adelaide Panattoni, Mariacristina Massimino, Antonella Lupetti, Emilia Ghelardi

{"title":"Dissecting the role of the MS‐ring protein FliF in Bacillus cereus flagella‐related functions","authors":"Diletta Mazzantini, Guendalina Gherardini, Virginia Rossi, Francesco Celandroni, Marco Calvigioni, Adelaide Panattoni, Mariacristina Massimino, Antonella Lupetti, Emilia Ghelardi","doi":"10.1111/mmi.15299","DOIUrl":"https://doi.org/10.1111/mmi.15299","url":null,"abstract":"The flagellar MS‐ring, uniquely constituted by FliF, is essential for flagellar biogenesis and functionality in several bacteria. The aim of this study was to dissect the role of FliF in the Gram‐positive and peritrichously flagellated Bacillus cereus. We demonstrate that fliF forms an operon with the upstream gene fliE. In silico analysis of B. cereus ATCC 14579 FliF identifies functional domains and amino acid residues that are essential for protein functioning. The analysis of a ΔfliF mutant of B. cereus, constructed in this study using an in frame markerless gene replacement method, reveals that the mutant is unexpectedly able to assemble flagella, although in reduced amounts compared to the parental strain. Nevertheless, motility is completely abolished by fliF deletion. FliF deprivation causes the production of submerged biofilms and affects the ability of B. cereus to adhere to gastrointestinal mucins. We additionally show that the fliF deletion does not compromise the secretion of the three components of hemolysin BL, a toxin secreted through the flagellar type III secretion system. Overall, our findings highlight the important role of B. cereus FliF in flagella‐related functions, being the protein required for complete flagellation, motility, mucin adhesion, and pellicle biofilms.","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":"160 1","pages":""},"PeriodicalIF":3.6,"publicationDate":"2024-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141730503","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Interpreting the role of antioxidants in vivo: A cautionary tale. 解读抗氧化剂在体内的作用：一个值得警惕的故事。

IF 2.6 2区生物学

Molecular Microbiology Pub Date : 2024-07-01 Epub Date: 2024-07-03 DOI: 10.1111/mmi.15292

Diana M Downs, Robert K Poole

{"title":"Interpreting the role of antioxidants in vivo: A cautionary tale.","authors":"Diana M Downs, Robert K Poole","doi":"10.1111/mmi.15292","DOIUrl":"10.1111/mmi.15292","url":null,"abstract":"Bacteria have a remarkable ability to sense environmental stresses and to respond to these stressors by adapting their metabolism and physiology. In recent publications, investigators have suggested that multiple stresses that cause cell death share the mechanistic feature of stimulating the formation of reactive oxygen species (ROS). A central piece of evidence cited in these claims is the ability of exogenous antioxidant compounds to mitigate stress-related cell death. The validity of attributing a positive effect of exogenous antioxidants to ROS-mediated stress is challenged by an important study by Korshunov and Imlay in this issue of Molecular Microbiology. This study reports biochemical data that convincingly show that some commonly used antioxidants quench oxidants orders of magnitude too slowly to have a significant effect on the concentration of ROS in the cell. Under conditions where antioxidants minimize cell death, they also slow growth. Significantly, slowing cell growth by other means has the same restorative effect as adding an antioxidant. Based on the solid biochemical and genetic data, Korshunov and Imlay make the case for discarding the use of antioxidants to diagnose conditions that generate increased internal ROS production.","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":" ","pages":"129-132"},"PeriodicalIF":2.6,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11260230/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141498520","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Bacterial chromatin proteins, transcription, and DNA topology: Inseparable partners in the control of gene expression. 细菌染色质蛋白、转录和 DNA 拓扑：基因表达控制中不可分割的伙伴。

IF 2.6 2区生物学

Molecular Microbiology Pub Date : 2024-07-01 Epub Date: 2024-06-07 DOI: 10.1111/mmi.15283

Christine M Hustmyer, Robert Landick

引用次数: 0

Antioxidants are ineffective at quenching reactive oxygen species inside bacteria and should not be used to diagnose oxidative stress. 抗氧化剂不能有效淬灭细菌体内的活性氧，因此不应被用来诊断氧化应激。

IF 2.6 2区生物学

Molecular Microbiology Pub Date : 2024-07-01 Epub Date: 2024-06-18 DOI: 10.1111/mmi.15286

Sergey Korshunov, James A Imlay

{"title":"Antioxidants are ineffective at quenching reactive oxygen species inside bacteria and should not be used to diagnose oxidative stress.","authors":"Sergey Korshunov, James A Imlay","doi":"10.1111/mmi.15286","DOIUrl":"10.1111/mmi.15286","url":null,"abstract":"A wide variety of stresses have been proposed to exert killing effects upon bacteria by stimulating the intracellular formation of reactive oxygen species (ROS). A key part of the supporting evidence has often been the ability of antioxidant compounds to protect the cells. In this study, some of the most-used antioxidants-thiourea, glutathione, N-acetylcysteine, and ascorbate-have been examined. Their ability to quench superoxide and hydrogen peroxide was verified in vitro, but the rate constants were orders of magnitude too slow for them to have an impact upon superoxide and peroxide concentrations in vivo, where these species are already scavenged by highly active enzymes. Indeed, the antioxidants were unable to protect the growth and ROS-sensitive enzymes of E. coli strains experiencing authentic oxidative stress. Similar logic posits that antioxidants cannot substantially quench hydroxyl radicals inside cells, which contain abundant biomolecules that react with them at diffusion-limited rates. Indeed, antioxidants were able to protect cells from DNA damage only if they were applied at concentrations that slow metabolism and growth. This protective effect was apparent even under anoxic conditions, when ROS could not possibly be involved, and it was replicated when growth was similarly slowed by other means. Experimenters should discard the use of antioxidants as a way of detecting intracellular oxidative stress and should revisit conclusions that have been based upon such experiments. The notable exception is that these compounds can effectively degrade hydrogen peroxide from environmental sources before it enters cells.","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":" ","pages":"113-128"},"PeriodicalIF":2.6,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141419951","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

The flavohemoglobin Yhb1 is a new interacting partner of the heme transporter Str3. 黄素血红蛋白 Yhb1 是血红素转运体 Str3 的一个新的相互作用伙伴。

IF 2.6 2区生物学

Molecular Microbiology Pub Date : 2024-07-01 Epub Date: 2024-05-22 DOI: 10.1111/mmi.15281

Florie Lo Ying Ping, Tobias Vahsen, Ariane Brault, Raphaël Néré, Simon Labbé

{"title":"The flavohemoglobin Yhb1 is a new interacting partner of the heme transporter Str3.","authors":"Florie Lo Ying Ping, Tobias Vahsen, Ariane Brault, Raphaël Néré, Simon Labbé","doi":"10.1111/mmi.15281","DOIUrl":"10.1111/mmi.15281","url":null,"abstract":"Nitric oxide (˙NO) is a free radical that induces nitrosative stress, which can jeopardize cell viability. Yeasts have evolved diverse detoxification mechanisms to effectively counteract ˙NO-mediated cytotoxicity. One mechanism relies on the flavohemoglobin Yhb1, whereas a second one requires the S-nitrosoglutathione reductase Fmd2. To investigate heme-dependent activation of Yhb1 in response to ˙NO, we use hem1Δ-derivative Schizosaccharomyces pombe strains lacking the initial enzyme in heme biosynthesis, forcing cells to assimilate heme from external sources. Under these conditions, yhb1+ mRNA levels are repressed in the presence of iron through a mechanism involving the GATA-type transcriptional repressor Fep1. In contrast, when iron levels are low, the transcription of yhb1+ is derepressed and further induced in the presence of the ˙NO donor DETANONOate. Cells lacking Yhb1 or expressing inactive forms of Yhb1 fail to grow in a hemin-dependent manner when exposed to DETANONOate. Similarly, the loss of function of the heme transporter Str3 phenocopies the effects of Yhb1 disruption by causing hypersensitivity to DETANONOate under hemin-dependent culture conditions. Coimmunoprecipitation and bimolecular fluorescence complementation assays demonstrate the interaction between Yhb1 and the heme transporter Str3. Collectively, our findings unveil a novel pathway for activating Yhb1, fortifying yeast cells against nitrosative stress.","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":" ","pages":"29-49"},"PeriodicalIF":2.6,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141081489","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

ppGpp is a dual-role regulator involved in balancing iron absorption and prodiginine biosynthesis in Pseudoalteromonas. ppGpp是一种双重作用调节器，参与平衡假交替单胞菌的铁吸收和原苷生物合成。

IF 2.6 2区生物学

Molecular Microbiology Pub Date : 2024-07-01 Epub Date: 2024-06-06 DOI: 10.1111/mmi.15285

Ning Wei, Fanglan Zha, Luosai Zhou, Hongyang Xu, Zhuangzhuang Liu, Qiu Meng, Tingheng Zhu, Jianhua Yin, Zhiliang Yu

{"title":"ppGpp is a dual-role regulator involved in balancing iron absorption and prodiginine biosynthesis in Pseudoalteromonas.","authors":"Ning Wei, Fanglan Zha, Luosai Zhou, Hongyang Xu, Zhuangzhuang Liu, Qiu Meng, Tingheng Zhu, Jianhua Yin, Zhiliang Yu","doi":"10.1111/mmi.15285","DOIUrl":"10.1111/mmi.15285","url":null,"abstract":"Iron is an essential element for microbial survival and secondary metabolism. However, excess iron availability and overloaded secondary metabolites can hinder microbial growth and survival. Microorganisms must tightly control iron homeostasis and secondary metabolism. Our previous studies have found that the stringent starvation protein A (SspA) positively regulates prodiginine biosynthesis by activating iron uptake in Pseudoalteromonas sp. strain R3. It is believed that the interaction between SspA and the small nucleotide ppGpp is important for iron to exert regulation functions. However, the roles of ppGpp in iron absorption and prodiginine biosynthesis, and the underlying relationship between ppGpp and SspA in strain R3 remain unclear. In this study, we found that ppGpp accumulation in strain R3 could be induced by limiting iron. In addition, ppGpp not only positively regulated iron uptake and prodiginine biosynthesis via increasing the SspA level but also directly repressed iron uptake and prodiginine biosynthesis independent of SspA, highlighting the finding that ppGpp can stabilize both iron levels and prodiginine production. Notably, the abolishment of ppGpp significantly increased prodiginine production, thus providing a theoretical basis for manipulating prodiginine production in the future. This dynamic ppGpp-mediated interaction between iron uptake and prodiginine biosynthesis has significant implications for understanding the roles of nutrient uptake and secondary metabolism for the survival of bacteria in unfavorable environments.","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":" ","pages":"68-80"},"PeriodicalIF":2.6,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141284283","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Chemoreceptors in Sinorhizobium meliloti require minimal pentapeptide tethers to provide adaptational assistance. 瓜萎镰刀菌（Sinorhizobium meliloti）的化学感受器需要最少的五肽系链来提供适应性帮助。

IF 2.6 2区生物学

Molecular Microbiology Pub Date : 2024-07-01 Epub Date: 2024-05-26 DOI: 10.1111/mmi.15282

Alfred Agbekudzi, Birgit E Scharf

{"title":"Chemoreceptors in Sinorhizobium meliloti require minimal pentapeptide tethers to provide adaptational assistance.","authors":"Alfred Agbekudzi, Birgit E Scharf","doi":"10.1111/mmi.15282","DOIUrl":"10.1111/mmi.15282","url":null,"abstract":"Sensory adaptation in bacterial chemotaxis is mediated by posttranslational modifications of methyl-accepting chemotaxis proteins (MCPs). In Escherichia coli, the adaptation proteins CheR and CheB tether to a conserved C-terminal receptor pentapeptide. Here,we investigated the function of the pentapeptide motif (N/D)WE(E/N)F in Sinorhizobium meliloti chemotaxis. Isothermal titration calorimetry revealed stronger affinity of the pentapeptides to CheR and activated CheB relative to unmodified CheB. Strains with mutations of the conserved tryptophan in one or all four MCP pentapeptides resulted in a significant decrease or loss of chemotaxis to glycine betaine, lysine, and acetate, chemoattractants sensed by pentapeptide-bearing McpX and pentapeptide-lacking McpU and McpV, respectively. Importantly, we discovered that the pentapeptide mediates chemotaxis when fused to the C-terminus of pentapeptide-lacking chemoreceptors via a flexible linker. We propose that adaptational assistance and a threshold number of available sites enable the efficient docking of adaptation proteins to the chemosensory array. Altogether, these results demonstrate that S. meliloti effectively utilizes a pentapeptide-dependent adaptation system with a minimal number of tethering units to assist pentapeptide-lacking chemoreceptors and hypothesize that the higher abundance of CheR and CheB in S. meliloti compared to E. coli allows for ample recruitment of adaptation proteins to the chemosensory array.","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":" ","pages":"50-67"},"PeriodicalIF":2.6,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141154422","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Multiple regulatory inputs including cell envelope stress orchestrate expression of the Escherichia coli rpoN operon. 包括细胞膜压力在内的多种调控输入协调着大肠杆菌 rpoN 操作子的表达。

IF 2.6 2区生物学

Molecular Microbiology Pub Date : 2024-07-01 Epub Date: 2024-05-21 DOI: 10.1111/mmi.15280

Florian Sikora, Lara Veronika Perko Budja, Olja Milojevic, Amelia Ziemniewicz, Przemyslaw Dudys, Boris Görke

{"title":"Multiple regulatory inputs including cell envelope stress orchestrate expression of the Escherichia coli rpoN operon.","authors":"Florian Sikora, Lara Veronika Perko Budja, Olja Milojevic, Amelia Ziemniewicz, Przemyslaw Dudys, Boris Görke","doi":"10.1111/mmi.15280","DOIUrl":"10.1111/mmi.15280","url":null,"abstract":"The rpoN operon, an important regulatory hub in Enterobacteriaceae, includes rpoN encoding sigma factor σ54, hpf involved in ribosome hibernation, rapZ regulating glucosamine-6-phosphate levels, and two genes encoding proteins of the nitrogen-related phosphotransferase system. Little is known about regulatory mechanisms controlling the abundance of these proteins. This study employs transposon mutagenesis and chemical screens to dissect the complex expression of the rpoN operon. We find that envelope stress conditions trigger read-through transcription into the rpoN operon from a promoter located upstream of the preceding lptA-lptB locus. This promoter is controlled by the envelope stress sigma factor E and response regulator PhoP is required for its full response to a subset of stress signals. σE also stimulates ptsN-rapZ-npr expression using an element downstream of rpoN, presumably by interfering with mRNA processing by RNase E. Additionally, we identify a novel promoter in the 3' end of rpoN that directs transcription of the distal genes in response to ethanol. Finally, we show that translation of hpf and ptsN is individually regulated by the RNA chaperone Hfq, perhaps involving small RNAs. Collectively, our work demonstrates that the rpoN operon is subject to complex regulation, integrating signals related to envelope stress and carbon source quality.","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":" ","pages":"11-28"},"PeriodicalIF":2.6,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141069594","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Nucleoid-associated proteins of mycobacteria come with a distinctive flavor 分枝杆菌的核糖体相关蛋白风味独特

IF 3.6 2区生物学

Molecular Microbiology Pub Date : 2024-06-22 DOI: 10.1111/mmi.15287

Meghna Santoshi, Priyanka Tare, Valakunja Nagaraja

引用次数: 0

Cleavage of an engulfment peptidoglycan hydrolase by a sporulation signature protease in Clostridioides difficile 难辨梭状芽孢杆菌中的一种孢子标志蛋白酶对吞噬肽聚糖水解酶的破坏作用

IF 3.6 2区生物学

Molecular Microbiology Pub Date : 2024-06-22 DOI: 10.1111/mmi.15291

Diogo Martins, Hailee N. Nerber, Charlotte G. Roughton, Amaury Fasquelle, Anna Barwinska-Sendra, Daniela Vollmer, Joe Gray, Waldemar Vollmer, Joseph A. Sorg, Paula S. Salgado, Adriano O. Henriques, Mónica Serrano

{"title":"Cleavage of an engulfment peptidoglycan hydrolase by a sporulation signature protease in Clostridioides difficile","authors":"Diogo Martins, Hailee N. Nerber, Charlotte G. Roughton, Amaury Fasquelle, Anna Barwinska-Sendra, Daniela Vollmer, Joe Gray, Waldemar Vollmer, Joseph A. Sorg, Paula S. Salgado, Adriano O. Henriques, Mónica Serrano","doi":"10.1111/mmi.15291","DOIUrl":"https://doi.org/10.1111/mmi.15291","url":null,"abstract":"In the model organism Bacillus subtilis, a signaling protease produced in the forespore, SpoIVB, is essential for the activation of the sigma factor σK, which is produced in the mother cell as an inactive pro-protein, pro-σK. SpoIVB has a second function essential to sporulation, most likely during cortex synthesis. The cortex is composed of peptidoglycan (PG) and is essential for the spore's heat resistance and dormancy. Surprisingly, the genome of the intestinal pathogen Clostridioides difficile, in which σK is produced without a pro-sequence, encodes two SpoIVB paralogs, SpoIVB1 and SpoIVB2. Here, we show that spoIVB1 is dispensable for sporulation, while a spoIVB2 in-frame deletion mutant fails to produce heat-resistant spores. The spoIVB2 mutant enters sporulation, undergoes asymmetric division, and completes engulfment of the forespore by the mother cell but fails to synthesize the spore cortex. We show that SpoIIP, a PG hydrolase and part of the engulfasome, the machinery essential for engulfment, is cleaved by SpoIVB2 into an inactive form. Within the engulfasome, the SpoIIP amidase activity generates the substrates for the SpoIID lytic transglycosylase. Thus, following engulfment completion, the cleavage and inactivation of SpoIIP by SpoIVB2 curtails the engulfasome hydrolytic activity, at a time when synthesis of the spore cortex peptidoglycan begins. SpoIVB2 is also required for normal late gene expression in the forespore by a currently unknown mechanism. Together, these observations suggest a role for SpoIVB2 in coordinating late morphological and gene expression events between the forespore and the mother cell.","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":"49 1","pages":""},"PeriodicalIF":3.6,"publicationDate":"2024-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141441604","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0