Expression of the gene cluster for chlorate metabolism in the chlorate-respiring bacterium Ideonella dechloratans
2012 (English)In: Biochimica et Biophysica Acta - Bioenergetics, ISSN 0005-2728, E-ISSN 1879-2650, Vol. 1817, 157-158 p.Article in journal, Meeting abstract (Other academic) Published
Ideonella dechloratans is a facultative anaerobe able to use chlorate as a terminal electron acceptor under anaerobic conditions. Two enzymes are necessary for the decomposition of chlorate to chloride and molecular oxygen; chlorate reductase (Clr) and chlorite dismutase (Cld). The genes for these two enzymes are close to each other in the genome and form, together with a cytochrome c and a mob B gene, a gene cluster for chlorate metabolism. The localization of the cyt c gene suggests a function in electron transport during chlorate reduction but the corresponding protein has not been found. We have addressed the questions of how the expression of Cld and Clr is regulated during the aerob/anaerob switch and if the cyt c gene is expressed in I. dechloratans. The enzyme activities of Cld and Clr were measured in extracts from cells grown at different conditions; aerobically or anaerobically . Both enzymes were found to be active in all samples and the activity increased upon transfer of the cells from aerobic to anaerobic conditions, by five times for Cld and more than 200 times for Clr. Relative mRNA levels of Cld and Clr were determined by qRT-PCR in RNA preparations from cells grown under the same conditions as for the enzyme activity measurements. mRNA from both genes was detected in all preparations but with ten times higher levels in samples from anaerobic conditions. This increase in mRNA level is on the same scale as the increase in enzyme activity for Cld but accounts for less than a tenth of the activity enhancement seen for Clr. A possible effect of chlorate was tested by the addition of chlorate under aerobic conditions but this resulted in neither increased enzyme activities nor increased mRNA levels. qRT-PCR was performed with primers specific for the cyt c gene and this gene was also found to be expressed at both aerobic and anaerobic conditions. In summary, the results show that chlorate respiration is activated by anaerobiosis but not by chlorate in I. dechloratans and that this activation occurs at the transcriptional level. Due to the much larger increase in enzyme activity compared to the increase in mRNA level, the activity of Clr also seems to be effected by other mechanisms. Detection of cyt c mRNA suggests that its gene product can be found and the function investigated.
Place, publisher, year, edition, pages
Elsevier, 2012. Vol. 1817, 157-158 p.
Research subject Biomedical Sciences; Chemistry
IdentifiersURN: urn:nbn:se:kau:diva-38481DOI: 10.1016/j.bbabio.2012.06.413ISI: 000308525400387OAI: oai:DiVA.org:kau-38481DiVA: diva2:896844