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The domains carrying the opposing activities in adenylyltransferase are separated by a central regulatory domain
Author(s) -
Clancy Paula,
Xu Yibin,
van Heeswijk Wally C.,
Vasudevan Subhash G.,
Ollis David L.
Publication year - 2007
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/j.1742-4658.2007.05820.x
Subject(s) - domain (mathematical analysis) , computational biology , chemistry , computer science , biology , mathematics , mathematical analysis
Adenylyltransferase is a bifunctional enzyme that controls the enzymatic activity of dodecameric glutamine synthetase in Escherichia coli by reversible adenylylation and deadenylylation. Previous studies showed that the two similar but chemically distinct reactions are carried out by separate domains within adenylyltransferase. The N‐terminal domain carries the deadenylylation activity, and the C‐terminal domain carries the adenylylation activity [Jaggi R, van Heeswijk WC, Westerhoff HV, Ollis DL & Vasudevan SG (1997) EMBO J 16 , 5562–5571]. In this study, we further map the domain junctions of adenylyltransferase on the basis of solubility and enzymatic analysis of truncation constructs, and show for the first time that adenylyltransferase has three domains: the two activity domains and a central, probably regulatory (R), domain connected by interdomain Q‐linkers (N‐Q1‐R‐Q2‐C). The various constructs, which have the opposing domain and or central domain removed, all retain their activity in the absence of their respective nitrogen status indicator, i.e. PII or PII‐UMP. A panel of mAbs to adenylyltransferase was used to demonstrate that the cellular nitrogen status indicators, PII and PII‐UMP, probably bind in the central regulatory domain to stimulate the adenylylation and deadenylylation reactions, respectively. In the light of these results, intramolecular signaling within adenylyltransferase is discussed.