5cnx | pdb_00005cnx
Crystal structure of Xaa-Pro aminopeptidase from Escherichia coli K12
Structural highlights
FunctionYPDF_ECOLI Hydrolyzes the N-terminal methionine when the next amino acid is alanine, proline or serine. The substrate preference for methionyl aminopeptidase activity is Pro > Ala > Ser. Also able to hydrolyze the Xaa-Pro peptide bond when the first amino acid is alanine, asparagine or methionine.[1] Publication Abstract from PubMedM24B peptidases cleaving Xaa-Pro bond in dipeptides are prolidases whereas those cleaving this bond in longer peptides are aminopeptidases-P. Bacteria have small aminopeptidases-P (36-39 kDa), which are diverged from canonical aminopeptidase-P of Escherichia coli (50 kDa). Structure-function studies of small aminopeptidases-P are lacking. We report crystal structures of small aminopeptidases-P from E. coli and Deinococcus radiodurans, and report substrate-specificities of these proteins and their ortholog from Mycobacterium tuberculosis. These are aminopeptidases-P, structurally close to small prolidases except for absence of dipeptide-selectivity loop. We noticed absence of this loop and conserved arginine in canonical archaeal prolidase (Maher et al., Biochemistry. 43, 2004, 2771-2783) and questioned its classification. Our enzymatic assays show that this enzyme is an aminopeptidase-P. Further, our mutagenesis studies illuminate importance of DXRY sequence motif in bacterial small aminopeptidases-P and suggest common evolutionary origin with human XPNPEP1/XPNPEP2. Our analyses reveal sequence/structural features distinguishing small aminopeptidases-P from other M24B peptidases. Structures and activities of widely conserved small prokaryotic aminopeptidases-P clarify classification of M24B peptidases.,Are VN, Kumar A, Goyal VD, Gotad SS, Ghosh B, Gadre R, Jamdar SN, Makde RD Proteins. 2018 Dec 11. doi: 10.1002/prot.25641. PMID:30536999[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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