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Glucose and related catabolite repressors are powerful inhibitors of pKM101-enhanced UV mutagenesis in Escherichia coli

journal contribution
posted on 2023-05-17, 20:19 authored by Mark AmbroseMark Ambrose, MacPhee, DG
When stationary phase Escherichia coli K12 trp (amber) cells were exposed to UV doses ranging from 180-540 J m(-2), we found that we could not recover any induced Trp+ revertants unless the irradiated cultures were first supplied with the Muc+ mutation-enhancing IncP plasmid pKM101 (by conjugation). We also found that the numbers of UV-induced Trp+ revertants recovered from pKM101+ cultures varied quite dramatically depending upon which of several commonly-used carbon sources were present in the post-irradiation plating medium, e.g., there were always significantly fewer revertants on minimal glucose plates than on minimal glycerol plates. More importantly, there were also fewer UV-induced revertants on glycerol + glucose plates than on 'glycerol-only' plates. We then tested two glucose-related compounds which are known to depress intracellular cyclic AMP (cAMP) levels even more effectively than glucose (glucose-6-phosphate and the non-utilisable methyl-alpha-D-glucopyranoside) and found that they too were able to exert powerfully antimutagenic effects in UV-treated pKM101-containing bacteria. Taken together, these results provide strong additional support for our working hypothesis that at least one component of the mutational pathway which operates in UV-irradiated pKM101-containing cells is extremely sensitive to classical cAMP-mediated catabolite repression.

History

Publication title

Mutation Research

Volume

422

Pagination

107-12

ISSN

0027-5107

Department/School

Tasmanian School of Medicine

Publisher

Elsevier Science Bv

Place of publication

Po Box 211, Amsterdam, Netherlands, 1000 Ae

Rights statement

Copyright 1998 Elsevier B.V.

Repository Status

  • Restricted

Socio-economic Objectives

Clinical health not elsewhere classified

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