In:
The FEBS Journal, Wiley, Vol. 281, No. 14 ( 2014-07), p. 3218-3227
Kurzfassung:
Available structures of HAMP domains suggest rotation as one potential mechanism in intraprotein signal transduction. It has been proposed that in poly‐ HAMP modules the signal sign is inverted with each additional HAMP . We examined signal transduction through the HAMP tandem domain from the phototaxis transducer of the halophilic archaeon N atronomonas pharaonis in membrane‐bound chimeras consisting of the E scherichia coli chemotaxis receptor for serine, T sr, as an input and the mycobacterial adenylyl cyclase R v3645 as an output domain, i.e. the basic chimera was ‘ T sr– N p HAMP tandem– R v3645 cyclase’. Neither of the N p HAMP units alone nor the N p HAMP tandem transduced a serine signal. After five targeted point mutations in the first α‐helix of N p HAMP 1 , the non‐functional N p HAMP modules combined into a functional HAMP tandem. 1 m m serine significantly inhibited cyclase activity (−35%; IC 50 = 30 μ m ) in disagreement with the structure‐based predictions. Surprisingly, replacement of N p AS 1 1 in the tandem by the respective AS 1 from HAMP T sr resulted in signal inversion, i.e. serine activated cyclase (+129%; EC 50 = 10 μ m ). Examination of 48 mutants of AS 1 1 in the HAMP tandem including two residues of a putative N ‐terminal control cable identified five residues in N p AS 1 1 which probably define different ground states of the output domain and thus affect the sign of signal output. The data question the predicted HAMP rotation as the predominant mechanism of intraprotein signal transduction and point to as yet unrecognized conformational motions of HAMP domains in intraprotein signaling.
Materialart:
Online-Ressource
ISSN:
1742-464X
,
1742-4658
DOI:
10.1111/febs.2014.281.issue-14
Sprache:
Englisch
Verlag:
Wiley
Publikationsdatum:
2014
ZDB Id:
2172518-4
SSG:
12
