{"title":"Preferential binding of ADP-bound mitochondrial HSP70 to the nucleotide exchange factor GRPEL1 over GRPEL2.","authors":"Pooja Manjunath, Gorazd Stojkovič, Liliya Euro, Svetlana Konovalova, Sjoerd Wanrooij, Kristian Koski, Henna Tyynismaa","doi":"10.1002/pro.5190","DOIUrl":null,"url":null,"abstract":"<p><p>Human nucleotide exchange factors GRPEL1 and GRPEL2 play pivotal roles in the ADP-ATP exchange within the protein folding cycle of mitochondrial HSP70 (mtHSP70), a crucial chaperone facilitating protein import into the mitochondrial matrix. Studies in human cells and mice have indicated that while GRPEL1 serves as an essential co-chaperone for mtHSP70, GRPEL2 has a role regulated by stress. However, the precise structural and biochemical mechanisms underlying the distinct functions of the GRPEL proteins have remained elusive. In our study, we present evidence revealing that ADP-bound mtHSP70 exhibits remarkably higher affinity for GRPEL1 compared to GRPEL2, with the latter experiencing a notable decrease in affinity upon ADP binding. Additionally, Pi assay showed that GRPEL1, but not GRPEL2, enhanced the ATPase activity of mtHSP70. Utilizing Alphafold modeling, we propose that the interaction between GRPEL1 and mtHSP70 can induce the opening of the nucleotide binding cleft of the chaperone, thereby facilitating the release of ADP, whereas GRPEL2 lacks this capability. Additionally, our findings suggest that the redox-regulated Cys87 residue in GRPEL2 does not play a role in dimerization but rather reduces its affinity for mtHSP70. Our findings on the structural and functional disparities between GRPEL1 and GRPEL2 may have implications for mitochondrial protein folding and import processes under varying cellular conditions.</p>","PeriodicalId":20761,"journal":{"name":"Protein Science","volume":null,"pages":null},"PeriodicalIF":4.5000,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11500471/pdf/","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Protein Science","FirstCategoryId":"99","ListUrlMain":"https://doi.org/10.1002/pro.5190","RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"BIOCHEMISTRY & MOLECULAR BIOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
Human nucleotide exchange factors GRPEL1 and GRPEL2 play pivotal roles in the ADP-ATP exchange within the protein folding cycle of mitochondrial HSP70 (mtHSP70), a crucial chaperone facilitating protein import into the mitochondrial matrix. Studies in human cells and mice have indicated that while GRPEL1 serves as an essential co-chaperone for mtHSP70, GRPEL2 has a role regulated by stress. However, the precise structural and biochemical mechanisms underlying the distinct functions of the GRPEL proteins have remained elusive. In our study, we present evidence revealing that ADP-bound mtHSP70 exhibits remarkably higher affinity for GRPEL1 compared to GRPEL2, with the latter experiencing a notable decrease in affinity upon ADP binding. Additionally, Pi assay showed that GRPEL1, but not GRPEL2, enhanced the ATPase activity of mtHSP70. Utilizing Alphafold modeling, we propose that the interaction between GRPEL1 and mtHSP70 can induce the opening of the nucleotide binding cleft of the chaperone, thereby facilitating the release of ADP, whereas GRPEL2 lacks this capability. Additionally, our findings suggest that the redox-regulated Cys87 residue in GRPEL2 does not play a role in dimerization but rather reduces its affinity for mtHSP70. Our findings on the structural and functional disparities between GRPEL1 and GRPEL2 may have implications for mitochondrial protein folding and import processes under varying cellular conditions.
期刊介绍:
Protein Science, the flagship journal of The Protein Society, is a publication that focuses on advancing fundamental knowledge in the field of protein molecules. The journal welcomes original reports and review articles that contribute to our understanding of protein function, structure, folding, design, and evolution.
Additionally, Protein Science encourages papers that explore the applications of protein science in various areas such as therapeutics, protein-based biomaterials, bionanotechnology, synthetic biology, and bioelectronics.
The journal accepts manuscript submissions in any suitable format for review, with the requirement of converting the manuscript to journal-style format only upon acceptance for publication.
Protein Science is indexed and abstracted in numerous databases, including the Agricultural & Environmental Science Database (ProQuest), Biological Science Database (ProQuest), CAS: Chemical Abstracts Service (ACS), Embase (Elsevier), Health & Medical Collection (ProQuest), Health Research Premium Collection (ProQuest), Materials Science & Engineering Database (ProQuest), MEDLINE/PubMed (NLM), Natural Science Collection (ProQuest), and SciTech Premium Collection (ProQuest).