PERIPLASMIC STRESS AND ECF SIGMA FACTORS

• Published in: Annual review of microbiology Vol. 55; no. 1; pp. 591 - 624
• Main Authors: Raivio, Tracy L, Silhavy, Thomas J
• Format: Journal Article
• Language: English
• Published: Palo Alto, CA 94303-0139 Annual Reviews 01-01-2001; 4139 El Camino Way, P.O. Box 10139 Annual Reviews, Inc; USA
• Subjects: Action of physical and chemical agents; Action of physical and chemical agents on bacteria; Bacterial Outer Membrane Proteins - metabolism; Bacterial Physiological Phenomena; Bacterial Proteins - metabolism; Bacteriology; Biological and medical sciences; Biosynthesis; Cellular signal transduction; Cytoplasm; envelope stress; Escherichia coli; Escherichia coli Proteins; Fimbriae, Bacterial - metabolism; Fundamental and applied biological sciences. Psychology; Heat-Shock Proteins - metabolism; Microbiology; Mycology; Periplasm - metabolism; Periplasm - physiology; Physiological aspects; Protein Folding; Protein Kinases - metabolism; Proteins; Sigma Factor - metabolism; Signal Transduction; United States; Functional response; Pathogenesis; Escherichia coli; Refolding; Biosynthesis; Protein A; Envelope; Cell wall; Stress; Response function; External; Bacteria; Cell; Variety; Enterobacteriaceae
• ISSN: 0066-4227; 1545-3251
• DOI: 10.1146/annurev.micro.55.1.591

Envelope stress responses play important pysiological roles in a variety of
processes, including protein folding, cell wall biosynthesis, and pathogenesis.
Many of these responses are controlled by extracytoplasmic function (ECF) sigma
factors that respond to external signals by means of a membrane-localized
anti-sigma factor. One of the best-characterized, ECF-regulated responses
is the σ
E
envelope stress response of
Escherichia coli
.
The σ
E
pathway ensures proper assembly of outer-membrane
proteins (OMP) by controlling expression of genes involved in OMP folding and
degradation in response to envelope stresses that disrupt these processes.
Prevailing evidence suggests that, in
E. coli
, a second envelope stress
response controlled by the Cpx two-component system ensures proper pilus
assembly. The sensor kinase CpxA recognizes misfolded periplasmic proteins,
such as those generated during pilus assembly, and transduces this signal to
the response regulator CpxR through conserved phosphotransfer reactions.
Phosphorylated CpxR activates transcription of periplasmic factors necessary
for pilus assembly.