TY  - JOUR
A1  - Heininger, Annika
A1  - Yusuf, Rahmi
A1  - Lawrence, Robert J.
A1  - Draheim, Roger R.
T1  - Identification of transmembrane helix 1 (TM1) surfaces important for EnvZ dimerisation and signal output
T2  - Acta biochimica et biophysica Sinica
N2  - The Escherichia coli sensor kinase EnvZ modulates porin expression in response to various stimuli, including extracellular osmolarity, the presence of procaine and interaction with an accessory protein, MzrA. Two major outer membrane porins, OmpF and OmpC, act as passive diffusion-limited pores that allow compounds, including certain classes of antibiotics such as β-lactams and fluoroquinolones, to enter the bacterial cell. Even though the mechanisms by which EnvZ detects and processes the presence of various stimuli are a fundamental component of microbial physiology, they are not yet fully understood. Here, we assess the role of TM1 during signal transduction in response to the presence of extracellular osmolarity. Various mechanisms of transmembrane communication have been proposed including rotation of individual helices within the transmembrane domain, dynamic movement of the membrane-distal portion of the cytoplasmic domain and regulated intra-protein unfolding. To assess these possibilities, we have created a library of single-Cys-containing EnvZ proteins in order to facilitate sulfhydryl-reactivity experimentation. Our results demonstrate that the major TM1-TM1' interface falls along a single surface consisting of residue positions 19, 23, 26, 30 and 34. In addition, we show that Cys substitutions within the N- and C-terminal regions of TM1 result in drastic changes to EnvZ signal output. Finally, we demonstrate that core residues within TM1 are responsible for both TM1 dimerisation and maintenance of steady-state signal output. Overall, our results suggest that no major rearrangement of the TM1-TM1' interface occurs during transmembrane communication in response to extracellular osmolarity. We conclude by discussing these results within the frameworks of several proposed models for transmembrane communication.
KW  - EnvZ signalling
KW  - Osmosensing
KW  - Porin regulation
KW  - Sulfhydryl-reactivity
KW  - Transmembrane communication
Y1  - 2017
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/44490
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-444907
SN  - 1745-7270
SN  - 0582-9879
SN  - 1672-9145
N1  - Under an Elsevier user license
VL  - 1858
IS  - 8
SP  - 1868
EP  - 1875
PB  - Oxford Univ. Press
CY  - Shanghai ; Oxford [u. a.]
ER  -