Submitted to: Journal of Industrial Microbiology and Biotechnology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/31/2006
Publication Date: 1/19/2007
Citation: He, Z., Parales, R.E., Spain, J.C., Johnson, G.R. 2007. Novel organization of catechol meta pathway genes in the nitrobenzene degrader comamonas sp. JS765 and its evolutionary implication. Journal of Industrial Microbiology and Biotechnology. 34:99-104. Interpretive Summary: Widespread environmental contamination with manmade aromatic compounds (organic chemicals containing one or more six-carbon rings and other groups) has occurred as a result of past industrial and agricultural practices. Biodegradation is a crucial removal mechanism for aromatic contaminants in the environment. There are questions as to how microorganisms acquire and/or organize relevant genes together to become capable of degrading these manmade compounds. In particular, have the relevant microbial genes evolved from common ancestor bacteria or have the genes gathered recently among bacteria while adapting to a contaminated environment? This work reports gene organization in a bacterium which is capable of degrading nitrobenzene (an aromatic compound which was one of the top 50 chemicals used in USA). The gene order in this bacterium is different from those published in the literature, thus revealing a novel type of gene organization. The gene organization we reported provides more data to analyze the origins of biodegradation pathways. Insight from this work may faster development of efficient biodegradation strategies to clean environmental contaminants.
Technical Abstract: The catechol meta cleavage pathway is one of the central metabolic pathways for the degradation of aromatic compounds. A novel organization of the pathway genes, different from that of classical soil microorganisms, has been observed in Sphingomonas sp HV3 and Pseudomonas sp. DJ77. In a Comamonas sp. JS765, cdoE encoding catechol 2,3-dioxygenase shares a common ancestry only with tdnC of a Pseudomonas putida strain, while codG encoding 2-hydroxymuconic semialdehyde dehydrogenase shows a higher degree of similarity to those genes in classical bacteria. Located between cdoE and cdoG are several putative genes, whose functions are unknown. These genes are not found in meta pathway operons of other microorganisms with the exception of cdoX2, which is similar to cmpX in strain HV3. Therefore, the gene cluster in JS765 reveals a third type of gene organization of the meta pathway.