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Functional coexistence of twin arsenic resistance systems in P seudomonas putida KT 2440
Author(s) -
PáezEspino A. David,
DuranteRodríguez Gonzalo,
Lorenzo Víctor
Publication year - 2015
Publication title -
environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.954
H-Index - 188
eISSN - 1462-2920
pISSN - 1462-2912
DOI - 10.1111/1462-2920.12464
Subject(s) - biology , operon , pseudomonas putida , bacteria , gene , arsenic , genetics , mutant , transcription (linguistics) , microbiology and biotechnology , chemistry , linguistics , philosophy , organic chemistry
Summary The genome of the soil bacterium P seudomonas putida KT 2440 bears two virtually identical arsRBCH operons putatively encoding resistance to inorganic arsenic species. Single and double chromosomal deletions in each of these ars clusters of this bacterium were tested for arsenic sensitivity and found that the contribution of each operon to the resistance to the metalloid was not additive, as either cluster sufficed to endow cells with high‐level resistance. However, otherwise identical traits linked to each of the ars sites diverged when temperature was decreased. Growth of the various mutants at 15°C (instead of the standard 30°C for P . putida ) uncovered that ars 2 affords a much higher resistance to A s ( III ) than the ars 1 counterpart. Reverse transcription polymerase chain reaction of arsB 1 and arsB 2 genes as well as lacZ fusions to the Pars 1 and Pars 2 promoters traced the difference to variations in transcription of the corresponding gene sets at each temperature. Functional redundancy may thus be selected as a stable condition – rather than just as transient state – if it affords one key activity to be expressed under a wider range of physicochemical settings. This seems to provide a straightforward solution to regulatory problems in environmental bacteria that thrive under changing scenarios.