Purification and characterization of Bacillus subtilis CheY.
Amino acid sequence comparison suggests that numerous proteins are common to the signal transduction pathways controlling chemotaxis in Bacillus subtilis and Escherichia coli. However, previous work has indicated several differences between the two systems. We have undertaken a comparative 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 phosphorylated in vitro by E. coli CheA, and dephosphorylation of CheY-P was enhanced by E. coli CheZ. Alteration of the putative site of phosphorylation in B. subtilis CheY, Asp54, eliminated chemotaxis in vivo, further confirming that phosphorylation is important for B. subtilis chemotaxis. Loss of CheY function resulted in tumbling behavior in B. subtilis. 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. subtilis CheY Asp10 mutant proteins also failed to cause tumbling in E. coli, consistent with a different interaction between CheY and the flagellar switch in the two species. Finally, B. subtilis adapted more rapidly to positive stimuli than negative stimuli, whereas the opposite is true of E. coli. We conclude that B. subtilis regulates its response to positive chemotactic stimuli by enhancing phosphorylation of chemotaxis proteins, whereas E. coli reduces phosphorylation in the same circumstance.
Bischoff
D S
DS
Department of Biochemistry, College of Medicine, University of Illinois, Urbana 61801.
Bourret
R B
RB
Kirsch
M L
ML
Ordal
G W
GW
D001412:Bacillus subtilis / Q000201:enzymology* / Q000235:genetics; D001426:Bacterial Proteins; D002633:Chemotaxis / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins; D005798:Genes, Bacterial / Q000235:genetics; D005812:Genes, Switch / Q000235:genetics; D000071677:Histidine Kinase; D008565:Membrane Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D000072236:Methyl-Accepting Chemotaxis Proteins; D016297:Mutagenesis, Site-Directed; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism; D015398:Signal Transduction; D013329:Structure-Activity Relationship; D013379:Substrate Specificity
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D000072236:Methyl-Accepting Chemotaxis Proteins; D011994:Recombinant Proteins; C000607606:cheY protein, E coli; D011494:Protein Kinases; D000071677:Histidine Kinase; C000607608:cheA protein, E coli