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Analysis of genes of tetrahydrofolate-dependent metabolism from cultivated spirochaetes and the gut community of the termite Zootermopsis angusticollis

Salmassi, Tina M. and Leadbetter, Jared R. (2003) Analysis of genes of tetrahydrofolate-dependent metabolism from cultivated spirochaetes and the gut community of the termite Zootermopsis angusticollis. Microbiology, 149 . pp. 2529-2537. ISSN 1350-0872. doi:10.1099/mic.0.26351-0.

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The hindguts of wood-feeding termites are the sites of intense, CO_2-reductive acetogenesis. This activity profoundly influences host nutrition and methane emissions. Homoacetogens previously isolated from diverse termites comprised novel taxa belonging to two distinct bacterial phyla, Firmicutes and Spirochaetes. Little else is known about either the diversity or abundance of homoacetogenic species present in any given termite or the genetic details underlying CO_2-reductive acetogenesis by Spirochaetes. A key enzyme of CO_2-reductive acetogenesis is formyltetrahydrofolate synthetase (FTHFS). A previously designed primer set was used to amplify FTHFS genes from three isolated termite-gut spirochaetes. Sequencing DNA flanking the FTHFS gene of Treponema strain ZAS-2 revealed genes encoding two acetogenesis-related enzymes, methenyltetrahydrofolate cyclohydrolase and methylenetetrahydrofolate dehydrogenase. Although termite-gut spirochaetes are only distantly related to clostridia at the ribosomal level, their tetrahydrofolate-dependent enzymes appear to be closely related. In contrast, homologous proteins identified in the non-homoacetogenic oral spirochaete Treponema denticola were only distantly related to those from clostridia and the termite-gut treponemes. Having demonstrated their utility with spirochaete pure cultures, the FTHFS primers were used to construct a 91-clone library from the termite-gut community DNA. From this, 19 DNA and eight amino acid FTHFS types were identified. Over 75 % of the retrieved clones formed a novel, coherent cluster with the FTHFS homologues obtained from the termite-gut treponemes. Thus, FTHFS gene diversity in the gut of the termite Zootermopsis angusticollis appears to be dominated by spirochaetes. The homoacetogenic capacity of termite-gut spirochaetes may have been acquired via lateral gene transfer from clostridia.

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Leadbetter, Jared R.0000-0002-7033-0844
Additional Information:© 2003 SGM. Received 14 March 2003; Revised 13 May 2003; Accepted 28 May 2003. This research was supported by infrastructure funds from the National Science Foundation (DBI-0107908), and a gift from the Schlumberger Foundation. We thank Rick Lovell for helpful advice and sharing data on an extensive FTHFS inventory in advance of its publication, and E. R. Leadbetter and our laboratory co-workers for their helpful comments.
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Schlumberger FoundationUNSPECIFIED
Record Number:CaltechAUTHORS:20130313-152236230
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:37508
Deposited By: Tony Diaz
Deposited On:20 Mar 2013 16:43
Last Modified:09 Nov 2021 23:29

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