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Catalytic activity of Peptidase N is required for adaptation of Escherichia coli to nutritional downshift and high temperature stress

Bhosale, Manoj and Kumar, Anujith and Das, Mrinmoy and Bhaskarla, Chetana and Agarwal, Vikas and Nandi, Dipankar (2012) Catalytic activity of Peptidase N is required for adaptation of Escherichia coli to nutritional downshift and high temperature stress. In: MICROBIOLOGICAL RESEARCH, 168 (1). pp. 56-64.

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Official URL: http://dx.doi.org/10.1016/j.micres.2012.06.003

Abstract

Peptidase N (PepN), the sole M1 family member in Escherichia coli, displays broad substrate specificity and modulates stress responses: it lowers resistance to sodium salicylate (NaSal)-induced stress but is required during nutritional downshift and high temperature (NDHT) stress. The expression of PepN does not significantly change during different growth phases in LB or NaSal-induced stress; however, PepN amounts are lower during NDHT stress. To gain mechanistic insights on the roles of catalytic activity of PepN in modulating these two stress responses, alanine mutants of PepN replacing E264 (GAMEN motif) and E298 (HEXXH motif) were generated. There are no major structural changes between purified wild type (WT) and mutant proteins, which are catalytically inactive. Importantly, growth profiles of Delta pepN upon expression of WT or mutant proteins demonstrated the importance of catalytic activity during NDHT but not NaSal-induced stress. Further fluorescamine reactivity studies demonstrated that the catalytic activity of PepN is required to generate higher intracellular amounts of free N-terminal amino acids; consequently, the lower growth of Delta pepN during NDHT stress increases with high amounts of casamino acids. Together, this study sheds insights on the expression and functional roles of the catalytic activity of PepN during adaptation to NDHT stress. (C) 2012 Elsevier GmbH. All rights reserved.

Item Type: Journal Article
Additional Information: Copyright for this article belongs to ELSEVIER GMBH, GERMANY
Keywords: Aminopeptidase;Cellular proteolysis;M1 family;Stress
Department/Centre: Division of Biological Sciences > Biochemistry
Depositing User: Francis Jayakanth
Date Deposited: 13 Feb 2013 10:39
Last Modified: 13 Feb 2013 10:39
URI: http://eprints.iisc.ac.in/id/eprint/45801

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