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Dual Role of a Biosynthetic Enzyme, CysK, in Contact Dependent Growth Inhibition in Bacteria.

DIR@IMTECH: CSIR-Institute of Microbial Technology

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Title Dual Role of a Biosynthetic Enzyme, CysK, in Contact Dependent Growth Inhibition in Bacteria.
 
Creator Kaundal, Soni
Uttam, Manju
Thakur, Krishan Gopal
 
Subject QR Microbiology
 
Description Contact dependent growth inhibition (CDI) is the phenomenon where CDI+ bacterial strain (inhibitor) inhibits the growth of CDI-strain (target) by direct cell to cell contact. CDI is mediated by cdiBAI gene cluster where CdiB facilitates the export of CdiA, an exotoxin, on the cell surface and CdiI acts as an immunity protein to protect CDI+ cells from autoinhibition. CdiA-CT, the C-terminal region of the toxin CdiA, from uropathogenic Escherichia coli strain 536 (UPEC536) is a latent tRNase that requires binding of a biosynthetic enzyme CysK (O-acetylserine sulfyhydrylase) for activation in the target cells. CdiA-CT can also interact simultaneously with CysK and immunity protein, CdiI, to form a ternary complex in UPEC536. But the role of CysK in the ternary complex is not clear. We studied the hydrodynamic, thermodynamic and kinetic parameters of binary and ternary complexes using AUC, ITC and SPR respectively, to investigate the role of CysK in UPEC536. We report that CdiA-CT binds CdiI and CysK with nanomolar range affinity. We further report that binding of CysK to CdiA-CT improves its affinity towards CdiI by ~40 fold resulting in the formation of a more stable complex with over ~130 fold decrease in dissociation rate. Thermal melting experiments also suggest the role of CysK in stabilizing CdiA-CT/CdiI complex as Tm of the binary complex shifts ~10°C upon binding CysK. Hence, CysK acts a modulator of CdiA-CT/CdiI interactions by stabilizing CdiA-CT/CdiI complex and may play a crucial role in preventing autoinhibition in UPEC536. This study reports a new moonlighting function of a biosynthetic enzyme, CysK, as a modulator of toxin/immunity interactions in UPEC536 inhibitor cells.
 
Publisher Public Library of Science
 
Date 2016
 
Type Article
PeerReviewed
 
Format application/pdf
 
Identifier http://crdd.osdd.net/open/1876/1/35.pdf
Kaundal, Soni and Uttam, Manju and Thakur, Krishan Gopal (2016) Dual Role of a Biosynthetic Enzyme, CysK, in Contact Dependent Growth Inhibition in Bacteria. PloS one, 11 (7). e0159844. ISSN 1932-6203
 
Relation http://crdd.osdd.net/open/1876/