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Please use this identifier to cite or link to this item: http://dspace.library.iitb.ac.in/jspui/handle/10054/12783

Title: Acid-induced loss of functional properties of bacterial cell division protein FtsZ: Evidence for an alternative conformation at acidic pH
Authors: SANTRA, MK
PANDA, D
Keywords: escherichia-coli
gtp hydrolysis
ruthenium red
molten globule
ring structure
in-vitro
tubulin
intermediate
apomyoglobin
binding
Issue Date: 2007
Publisher: WILEY-LISS
Citation: PROTEINS-STRUCTURE FUNCTION AND BIOINFORMATICS, 67(1), 177-188
Abstract: Several types of bacteria live in highly acidic environments. Since the assembly of FtsZ is important for bacterial cytokinesis, the effects of pH on the assembly and structural properties of FtsZ were examined. FtsZ retained GTP binding ability but lost GTPase activity at pH 2.5. In the presence of GTP, FtsZ formed protofilaments at pH 7 while it formed aggregates instead of protofilaments at pH 2.5, indicating that GTP hydrolysis is important for the assembly of FtsZ into protofilaments. Further, the acid-inactivated state of FtsZ recovered its structural and functional properties upon refolding at pH 7, indicating that the cellular functions of FtsZ may be restored after removal of the external stress. In addition, the affinity of 1-anilinonaphthalene-8-sulfonic acid (ANS) binding to FtsZ was found to be higher at pH 2.5 than at pH 7. FtsZ-ANS complex had a higher quantum yield and lifetime at pH 2.5 than at pH 7. However, the secondary structures of FtsZ were similar at pH 7 and 2.5, indicating that FtsZ attained an alternatively folded state (A) at pH 2.5, which has some characteristics of a molten-globule-like state. The A state was more stable than the native state (N) against urea-induced unfolding. The transition from N to A state involves the formation of aggregates of FtsZ (1). The association of FtsZ monomers occurred in the narrow pH range (3.2-2.8) and it was found to be a fully reversible process. The results suggest that a productive intermediate M forms in the acid-induced unfolding pathway of FtsZ and that the unfolding pathway may be minimally described as N reversible arrow I reversible arrow A. Proteins 2007;67:177-188. (c) 2007 Wiley-Liss, Inc.
URI: http://dx.doi.org/10.1002/prot.21178
http://dspace.library.iitb.ac.in/xmlui/handle/10054/12783
http://hdl.handle.net/10054/12783
ISSN: 0887-3585
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