PURIFICATION AND CHARACTERIZATION OF BACILLUS-SUBTILIS CHEY

Citation
Ds. Bischoff et al., PURIFICATION AND CHARACTERIZATION OF BACILLUS-SUBTILIS CHEY, Biochemistry, 32(35), 1993, pp. 9256-9261
Citations number
47
Categorie Soggetti
Biology
Journal title
ISSN journal
00062960
Volume
32
Issue
35
Year of publication
1993
Pages
9256 - 9261
Database
ISI
SICI code
0006-2960(1993)32:35<9256:PACOBC>2.0.ZU;2-Y
Abstract
Amino acid sequence comparison suggests that numerous proteins are com mon to the signal transduction pathways controlling chemotaxis in Baci llus subtilis and Escherichia coli. However, previous work has indicat ed several differences between the two systems. We have undertaken a c omparative study of the roles of the CheY protein in chemotaxis by B. subtilis and E. coli. Although CheY from the two species share only 36 % amino acid sequence identity, purified B. subtilis CheY was phosphor ylated in vitro by E. coli CheA, and dephosphorylation of CheY-P was e nhanced by E. coli CheZ. Alteration of the putative site of phosphoryl ation in B. subtilis CheY, Asp54, eliminated chemotaxis in vivo, furth er confirming that phosphorylation is important for B. subtilis chemot axis. Loss of CheY function resulted in tumbling behavior in B. subtil is. Introduction of positively charged residues in place of Asp10 of B . subtilis CheY abolished function, whereas the corresponding changes in E. coli CheY apparently result in constitutive activation. The B. s ubtilis CheY Asp10 mutant proteins also failed to cause tumbling in E. coli, consistent with a different interaction between CheY and the fl agellar switch in the two species. Finally, B. subtilis adapted more r apidly to positive stimuli than negative stimuli, whereas the opposite is true of E. coli. We conclude that B. subtilis regulates its respon se to positive chemotactic stimuli by enhancing phosphorylation of che motaxis proteins, whereas E. coli reduces phosphorylation in the same circumstance.