The identification of the transcriptional regulator CRP in Aeromonas hydrophila JMP636 and its involvement in amylase production and the 'acidic toxicity' effect.
OBJECTIVE
The physiological examination of amylase production by Aeromonas hydrophila JMP636 and identification of the mechanism of regulation.


RESULTS
Aeromonas hydrophila JMP636 was grown with single, then dual carbon sources; the growth cycle was followed and amylase activity throughout was monitored. The levels of cAMP, a known secondary messenger for the regulatory gene crp, were also examined. Amylase activity was regulated by catabolite repression. Physiological studies revealed that JMP636 exhibited both diauxic growth, with two carbon sources, and the 'acid toxicity' effect on glucose. The crp gene was cloned, expressed and inactivated from the JMP636 chromosome. Catabolite repression of amylase production and the 'acid toxicity' effect both require crp and were linked to cAMP levels.


CONCLUSIONS
Regulation of amylase production was predicted to follow the model CRP-mediated cAMP-dependent Escherichia coli catabolite regulation system.


CONCLUSIONS
This work provides an understanding of the physiology of the opportunistic pathogen Aer. hydrophila through identification of the mechanism of catabolite repression of amylase production and the existence of crp within this cell. It also provides a broader knowledge of global gene regulation and suggests regulatory mechanisms of other Aer. hydrophila gene/s.
Kidd
S P
SP
School of Biosciences, University of Birmingham, Edgbaston, UK. s.p.kidd@bham.ac.uk
Pemberton
J M
JM
D016980:Aeromonas hydrophila / Q000235:genetics / Q000378:metabolism*; D000681:Amylases / Q000096:biosynthesis* / Q000633:toxicity; D050260:Carbohydrate Metabolism; D000242:Cyclic AMP / Q000378:metabolism; D002373:Cyclic AMP Receptor Protein / Q000235:genetics / Q000378:metabolism*; D005809:Genes, Regulator / Q000235:genetics; D005947:Glucose / Q000378:metabolism; D006863:Hydrogen-Ion Concentration
D002373:Cyclic AMP Receptor Protein; D000242:Cyclic AMP; D000681:Amylases; D005947:Glucose