Residues at the cytoplasmic end of transmembrane helix 2 determine the signal output of the TarEc chemoreceptor

Baseline signal output and communication between the periplasmic and cytoplasmic domains of the Escherichia coli aspartate chemoreceptor Tar(Ec) are both strongly influenced by residues at the C-terminus of transmembrane helix 2 (TM2). In particular, the cytoplasmic aromatic anchor, composed of resi...

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Bibliographic Details
Published in:Biochemistry (Easton) 2013-04, Vol.52 (16), p.2729-2738
Main Authors: Adase, Christopher A, Draheim, Roger R, Rueda, Garrett, Desai, Raj, Manson, Michael D
Format: Article
Language:English
Subjects:
Aspartic Acid - metabolism
Chemotaxis - physiology
Cytoplasm - metabolism
Escherichia coli Proteins - chemistry
Escherichia coli Proteins - genetics
Escherichia coli Proteins - metabolism
Glycine - metabolism
Methylation
Mutation
Phenylalanine - metabolism
Protein Structure, Tertiary
Receptors, Cell Surface - chemistry
Receptors, Cell Surface - genetics
Receptors, Cell Surface - metabolism
Signal Transduction
Tyrosine - metabolism
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Summary:Baseline signal output and communication between the periplasmic and cytoplasmic domains of the Escherichia coli aspartate chemoreceptor Tar(Ec) are both strongly influenced by residues at the C-terminus of transmembrane helix 2 (TM2). In particular, the cytoplasmic aromatic anchor, composed of residues Trp-209 and Tyr-210 in wild-type Tar(Ec), is important for determining the CheA kinase-stimulating activity of the receptor and its ability to respond to chemoeffector-induced stimuli. Here, we have studied the effect on Tar(Ec) function of the six-residue sequence at positions 207-212. Moving various combinations of aromatic residues among these positions generates substantial changes in receptor activity. Trp has the largest effect on function, both in maintaining normal activity and in altering activity when it is moved. Tyr has a weaker effect, and Phe has the weakest; however, all three aromatic residues can alter signal output when they are placed in novel positions. We also find that Gly-211 plays an important role in receptor function, perhaps because of the flexibility it introduces into the TM2-HAMP domain connector. The conservation of this Gly residue in the high-abundance chemoreceptors of E. coli and Salmonella enterica suggests that it may be important for the nuanced, bidirectional transmembrane signaling that occurs in these proteins.
ISSN:1520-4995
DOI:10.1021/bi4002002