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dc.contributor.authorGumpena, Rajesh
dc.contributor.authorKishor, Chandan
dc.contributor.authorGanji, Roopa Jones
dc.contributor.authorJain, Nishant
dc.contributor.authorAddlagatta, Anthony
dc.description.abstractEscherichia coli aminopeptidase N (ePepN) belongs to the gluzincin family of M1 class metalloproteases that share a common primary structure with consensus zinc binding motif (HEXXH-(X18)-E) and an exopeptidase motif (GXMEN) in the active site. There is one amino acid, E121 in Domain I that blocks the extended active site grove of the thermolysin like catalytic domain (Domain II) limiting the substrate to S1 pocket. E121 forms a part of the S1 pocket, while making critical contact with the amino-terminus of the substrate. In addition, the carboxylate of E121 forms a salt bridge with K319 in Domain II. Both these residues are absolutely conserved in ePepN homologs. Analogous Glu-Asn pair in tricon interacting factor F3 (F3) and Gln-Asn pair in human leukotriene A4 hydrolase (LTA4H) are also conserved in respective homologs. Mutation of either of these residues individually or together substantially reduced or entirely eliminated enzymatic activity. In addition, thermal denaturation studies suggest that the mutation at K319 destabilizes the protein as much as by 3.7°C, while E121 mutants were insensitive. Crystal structure of E121Q mutant reveals that the enzyme is inactive due to the reduced S1 subsite volume. Together, data presented here suggests that ePepN, F3, and LTA4H homologs adopted a divergent evolution that includes E121-K319 or its analogous pairs, and these cannot be interchanged.
dc.publisherWiley-Blackwell Publishing, Inc.
dc.relation.ispartofjournalProtein Science
dc.subject.fieldofresearchBiochemistry and Cell Biology not elsewhere classified
dc.subject.fieldofresearchBiochemistry and Cell Biology
dc.subject.fieldofresearchComputation Theory and Mathematics
dc.subject.fieldofresearchOther Information and Computing Sciences
dc.titleGlu121-Lys319 salt bridge between catalytic and N-terminal domains is pivotal for the activity and stability of Escherichia coli aminopeptidase N
dc.typeJournal article
dc.type.descriptionC1 - Articles
dc.type.codeC - Journal Articles
gro.hasfulltextNo Full Text
gro.griffith.authorKishor, Chandan

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