Primary Citation of Related Structures: 3N75, 3Q16
PubMed Abstract:
The Escherichia coli inducible lysine decarboxylase, LdcI/CadA, together with the inner-membrane lysine-cadaverine antiporter, CadB, provide cells with protection against mild acidic conditions (pH∼5). To gain a better understanding of the molecular processes underlying the acid stress response, the X-ray crystal structure of LdcI was determined ...
The Escherichia coli inducible lysine decarboxylase, LdcI/CadA, together with the inner-membrane lysine-cadaverine antiporter, CadB, provide cells with protection against mild acidic conditions (pH∼5). To gain a better understanding of the molecular processes underlying the acid stress response, the X-ray crystal structure of LdcI was determined. The structure revealed that the protein is an oligomer of five dimers that associate to form a decamer. Surprisingly, LdcI was found to co-crystallize with the stringent response effector molecule ppGpp, also known as the alarmone, with 10 ppGpp molecules in the decamer. ppGpp is known to mediate the stringent response, which occurs in response to nutrient deprivation. The alarmone strongly inhibited LdcI enzymatic activity. This inhibition is important for modulating the consumption of lysine in cells during acid stress under nutrient limiting conditions. Hence, our data provide direct evidence for a link between the bacterial acid stress and stringent responses.
Related Citations:
Crystallization and preliminary X-ray analysis of the inducible lysine decarboxylase from Escherichia coli. Alexopoulos, E., Kanjee, U., Snider, J., Houry, W.A., Pai, E.F. (2008) Acta Crystallogr Sect F Struct Biol Cryst Commun 64(8): 700
Organizational Affiliation:
Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada.
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