Research article
- BipA GTPase function and abundance regulate ribosome biogenesis and envelope homeostasis during cold adaptation in Escherichia coli
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Yubin Lee, Eunsil Choi, Yeonwoo Jang, Yaesol Cho, Jihwan Hwang
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Received August 18, 2026 Accepted October 19, 2026 Published online November 10, 2026
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DOI: https://doi.org/10.71150/jm.2608017
[Epub ahead of print]
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Abstract
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Supplementary Material
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BipA is a conserved ribosome-associated GTPase that supports bacterial stress adaptation. It participates in 50S ribosome assembly and envelope stress responses; however, it is not known whether both functions depend on its GTPase activity. In this study, we investigated Escherichia coli strains carrying chromosomal D74A or N128D substitutions in the conserved GTPase motifs of BipA. Both mutants displayed severe cold-sensitive growth defects that were similar to those of the ΔbipA strain. At low temperatures, 50S ribosome assembly was defective and immature ribosomal particles accumulated. Ribosome-binding analysis revealed that the mutant BipA had a lower association with ribosomal fractions. The mutants exhibited altered lipopolysaccharide profiles and envelope phenotypes, including increased capsule production, reduced biofilm formation and motility, and increased cell width and length. These phenotypes were most notable at low temperatures, indicating activation of the Rcs (Regulator of Capsule Synthesis) phosphorelay. We next examined the effects of BipA abundance on cellular physiology. BipA expression was influenced by both start-codon identity and the downstream coding context. BipA overexpression impaired growth and induced pronounced cell elongation at both optimal and low temperatures, indicating that proper control of BipA abundance is important for cellular homeostasis. Furthermore, the increased susceptibility of the ΔbipA strain to ampicillin at low temperatures suggested an association between BipA and peptidoglycan homeostasis. Together, these findings suggest that BipA GTPase function is required to maintain ribosome biogenesis and envelope homeostasis during cold adaptation, and that proper control of BipA abundance is also important for maintaining cellular physiology.
Research Support, Non-U.S. Gov't
- In silico analysis and experimental validation of lipoprotein and novel Tat signal peptides processing in Anabaena sp. PCC7120
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Sonika Kumari , Akhilesh Kumar Chaurasia
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J. Microbiol. 2015;53(12):837-846. Published online December 2, 2015
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DOI: https://doi.org/10.1007/s12275-015-5281-3
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Abstract
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Signal peptide (SP) plays a pivotal role in protein translocation.
Lipoprotein- and twin arginine translocase (Tat) dependent
signal peptides were studied in All3087, a homolog of
competence protein of Synechocystis PCC6803 and in two
putative alkaline phosphatases (ALPs, Alr2234 and Alr4976),
respectively. In silico analysis of All3087 is shown to possess
the characteristics feature of competence proteins such as
helix-hairpin-helix, N and C-terminal HKD endonuclease
domain, calcium binding domain and N-terminal lipoprotein
signal peptide. The SP recognition-cleavage site in All3087
was predicted (AIA-AC) using SignalP while further in-depth
analysis using Pred-Lipo and WebLogo analysis for consensus
sequence showed it as IAA-C. Activities of putative
ALPs were confirmed by heterologous overexpression, activity
assessment and zymogram analysis. ALP activity in
Anabaena remains cell bound in log-phase, but during late
log/stationary phase, an enhanced ALP activity was detected
in extracellular milieu. The enhancement of ALP activity
during stationary phase was not only due to inorganic phosphate
limitation but also contributed by the presence of novel
bipartite Tat-SP. The Tat signal transported the folded active
ALPs to the membrane, followed by anchoring into the
membrane and successive cleavage enabling transportation
of the ALPs to the extracellular milieu, because of bipartite
architecture and processing of transit Tat-SP.
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Citations
Citations to this article as recorded by

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