Author:
Pérez-Mendoza Daniel,Rodríguez-Carvajal Miguel Ángel,Romero-Jiménez Lorena,Farias Gabriela de Araujo,Lloret Javier,Gallegos María Trinidad,Sanjuán Juan
Abstract
An artificial increase of cyclic diguanylate (c-di-GMP) levels inSinorhizobium meliloti8530, a bacterium that does not carry known cellulose synthesis genes, leads to overproduction of a substance that binds the dyes Congo red and calcofluor. Sugar composition and methylation analyses and NMR studies identified this compound as a linear mixed-linkage (1→3)(1→4)-β-d-glucan (ML β-glucan), not previously described in bacteria but resembling ML β-glucans found in plants and lichens. This unique polymer is hydrolyzed by the specific endoglucanase lichenase, but, unlike lichenan and barley glucan, it generates a disaccharidic →4)-β-d-Glcp-(1→3)-β-d-Glcp-(1→ repeating unit. A two-gene operonbgsBArequired for production of this ML β-glucan is conserved among several genera within the order Rhizobiales, wherebgsAencodes a glycosyl transferase with domain resemblance and phylogenetic relationship to curdlan synthases and to bacterial cellulose synthases. ML β-glucan synthesis is subjected to both transcriptional and posttranslational regulation.bgsBAtranscription is dependent on the exopolysaccharide/quorum sensing ExpR/SinI regulatory system, and posttranslational regulation seems to involve allosteric activation of the ML β-glucan synthase BgsA by c-di-GMP binding to its C-terminal domain. To our knowledge, this is the first report on a linear mixed-linkage (1→3)(1→4)-β-glucan produced by a bacterium. TheS.melilotiML β-glucan participates in bacterial aggregation and biofilm formation and is required for efficient attachment to the roots of a host plant, resembling the biological role of cellulose in other bacteria.
Funder
Ministerio de Economia y Competitividad
Consejería Economía, Innovación, Ciencia y Empleo, Junta de Andalucia
CSIC
Publisher
Proceedings of the National Academy of Sciences
Cited by
60 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献