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The length of glycine-rich linker in DNA-binding domain is critical for optimal functioning of quorum-sensing master regulatory protein HapR.

DIR@IMTECH: CSIR-Institute of Microbial Technology

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Title The length of glycine-rich linker in DNA-binding domain is critical for optimal functioning of quorum-sensing master regulatory protein HapR.
 
Creator Singh, Naorem Santa
Kachhap, Sangita
Singh, Richa
Mishra, Rahul Chandra
Singh, Balvinder
Raychaudhuri, Saumya
 
Subject QR Microbiology
 
Description HapR is a quorum-sensing master regulatory protein in Vibrio cholerae. Though many facts are known regarding its structural and functional aspects, much still can be learnt from natural variants of this wild-type protein. While unraveling the underlying cause of functional inertness of a natural variant (HapRV2), the significance of a conserved glycine residue at position 39 in a glycine-rich linker in DNA-binding domain comes into light. This work aims at investigating how the length of glycine-rich linker (R(33)GIGRGG(39)) bridging helices α1 and α2 modulates the functionality of HapR. In pursuit of our interest, glycine residues were inserted after terminal glycine (G39) of the linker in a sequential manner. To evaluate functionality, all the glycine linker variants were subjected to a battery of performance tests under various conditions. Combined in vitro and in vivo results clearly demonstrated a gradual functional impairment of HapR linker variants coupled with increasing length of glycine-rich linker and finally, linker variant harboring four glycine residues resulted in a functionally compromised protein with significant loss of communication with cognate DNAs. Molecular dynamics studies of modeled HapR linker variants in complex with cognate promoter region show that residues namely Ser50, Thr53 and Asn56 are involved in varying degree of interactions with different nucleotides of HapR-DNA complex. The diminished functionality between variants and DNA appears to result from reduced or no interactions between Phe55 and nucleotides of cognate DNA as observed during simulations.
 
Publisher Springer
 
Date 2014-12
 
Type Article
PeerReviewed
 
Relation http://link.springer.com/article/10.1007%2Fs00438-014-0878-5
http://crdd.osdd.net/open/1674/
 
Identifier Singh, Naorem Santa and Kachhap, Sangita and Singh, Richa and Mishra, Rahul Chandra and Singh, Balvinder and Raychaudhuri, Saumya (2014) The length of glycine-rich linker in DNA-binding domain is critical for optimal functioning of quorum-sensing master regulatory protein HapR. Molecular genetics and genomics , 289 (6). pp. 1171-82. ISSN 1617-4623