4q4t
From Proteopedia
Structure of the Resuscitation Promoting Factor Interacting protein RipA mutated at E444
Structural highlights
Function[RIPA_MYCTU] Peptidoglycan endopeptidase that cleaves the bond between D-glutamate and meso-diaminopimelate. Binds and degrades high-molecular weight peptidoglycan from a number of Actinobacteria; activity is increased in the presence of RpfB and inhibited by PBP1A (ponA1). Required for normal separation of daughter cells after cell division and for cell wall integrity. Required for host cell invasion and intracellular survival in host macrophages.[1] [2] [3] [4] [5] Publication Abstract from PubMedRipA is a key cysteine protease of Mycobacterium tuberculosis as it is responsible for bacterial daughter-cell separation. Although it is an important target for antimicrobial development, its mechanism of action and its interaction pattern with its substrate are hitherto unknown. By combining crystallographic and mutational studies with functional assays and molecular modelling, it is shown that the catalytic activity of the enzyme relies on a Cys-His-Glu triad and the impact of the mutation of each residue of the triad on the structure and function of RipA is analysed. Unexpectedly, the crystallographic analyses reveal that mutation of the glutamic acid to alanine results in inversion of the configuration of the catalytic cysteine. The consequent burial of the catalytic cysteine side chain explains the enzyme inactivation upon mutation. These data point to a novel role of the acidic residue often present in the triad of cysteine proteases as a supervisor of cysteine configuration through preservation of the local structural integrity. Mutational and structural study of RipA, a key enzyme in Mycobacterium tuberculosis cell division: evidence for the L-to-D inversion of configuration of the catalytic cysteine.,Squeglia F, Ruggiero A, Romano M, Vitagliano L, Berisio R Acta Crystallogr D Biol Crystallogr. 2014 Sep 1;70(Pt 9):2295-300. doi:, 10.1107/S1399004714013674. Epub 2014 Aug 29. PMID:25195744[6] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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