The Open Microbiology Journal


ISSN: 1874-2858 ― Volume 10, 2016

Regulation of clpQ+Y+ (hslV+U+) Gene Expression in Escherichia coli



Hsiang-Yun Lien1, Chien-Hung Yu1, Chung-Ming Liou2, Whi Fin Wu1, 2, *
1 Department of Agricultural Chemistry, National Taiwan University, Taipei (106), Taiwan, R.O.C
2 Department of Biochemical Science and Technology, Institute of Microbiology and Biochemistry

Abstract

The Escherichia coli ClpYQ (HslUV) complex is an ATP-dependent protease, and the clpQ+Y+ (hslV+U+) operon encodes two heat shock proteins, ClpQ and ClpY, respectively. The transcriptional (op) or translational (pr) clpQ+::lacZ fusion gene was constructed, with the clpQ+Y+ promoter fused to a lacZ reporter gene. The clpQ+::lacZ (op or pr) fusion gene was each crossed into lambda phage. The λclpQ+::lacZ+ (op), a transcriptional fusion gene, was used to form lysogens in the wild-type, rpoH or/and rpoS mutants. Upon shifting the temperature up from 30 °C to 42 °C, the wild-type λclpQ+::lacZ+ (op) demonstrates an increased β-galactosidase (βGal) activity. However, the βGal activity of clpQ+::lacZ+ (op) was decreased in the rpoH and rpoH rpoS mutants but not in the rpoS mutant. The levels of clpQ+::lacZ+ mRNA transcripts correlated well to their βGal activity. Similarly, the expression of the clpQ+::lacZ+ gene fusion was nearly identical to the clpQ+Y+ transcript under the in vivo condition. The clpQm1::lacZ+, containing a point mutation in the -10 promoter region for RpoH binding, showed decreased βGal activity, independent of activation by RpoH. We conclude that RpoH itself regulates clpQ+Y+ gene expression. In addition, the clpQ+Y+ message carries a conserved 71 bp at the 5’ untranslated region (5’UTR) that is predicted to form the stem-loop structure by analysis of its RNA secondary structure. The clpQm2Δ40::lacZ+, with a 40 bp deletion in the 5’UTR, showed a decreased βGal activity. In addition, from our results, it is suggested that this stem-loop structure is necessary for the stability of the clpQ+Y+ message.

Key Words: Promoter activity, Gene regulation, E. coli, ClpYQ (HslUV), ATP-dependent protease, 5’ stem-loop structure, mRNA stability.


Article Information


Identifiers and Pagination:

Year: 2009
Volume: 3
First Page: 29
Last Page: 39
Publisher Id: TOMICROJ-3-29
DOI: 10.2174/1874285800903010029

Article History:

Received Date: 11/2/2009
Revision Received Date: 17/2/2009
Acceptance Date: 24/2/2009
Electronic publication date: 17/3/2009
Collection year: 2009

© Lien et al.; Licensee Bentham Open.

open-access license: This is an open access article licensed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted, non-commercial use, distribution and reproduction in any medium, provided the work is properly cited.


* Address correspondence to this author at the Department of Agricultural Chemistry, National Taiwan University, Taipei (106), Taiwan, R.O.C. Tel: (8862)-3366-2212; or (8862)-3366-4818; Fax: (8862)-2363-3123; E-mail: whifinwu@ntu.edu.tw


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