title: The endo-beta-mannanase gene families in Arabidopsis, rice, and poplar.
abstract: Mannans are widespread hemicellulosic polysaccharides in plant cell walls. Hydrolysis of the internal beta-1,4-D: -mannopyranosyl linkage in the backbone of mannans is catalyzed by endo-beta-mannanase. Plant endo-beta-mannanase has been well studied for its function in seed germination. Its involvement in other plant biological processes, however, remains poorly characterized or elusive. The completed genome sequences of Arabidopsis (Arabidopsis thaliana), rice (Oryza sativa), and poplar (Populus trichocarpa) provide an opportunity to conduct comparative genomic analysis of endo-beta-mannanase genes in these three species. In silico sequence analysis led to the identification of eight, nine and 11 endo-beta-mannanase genes in the genomes of Arabidopsis, rice, and poplar, respectively. Sequence comparisons revealed the conserved amino acids and motifs that are critical for the active site of endo-beta-mannanases. Intron/exon structure analysis in conjunction with phylogenetic analysis implied that both intron gain and intron loss has played roles in the evolution of endo-beta-mannanase genes. The phylogenetic analysis that included the endo-beta-mannanases from plants and other organisms implied that plant endo-beta-mannanases have an ancient evolutionary origin. Comprehensive expression analysis of all Arabidopsis and rice endo-beta-mannanase genes showed divergent expression patterns of individual genes, suggesting that the enzymes encoded by these genes, while carrying out the same biochemical reaction, are involved in diverse biological processes.
authors.affiliation: Department of Plant Sciences, University of Tennessee, 2431 Joe Johnson Drive, Knoxville, TN 37996, USA.
authors.forename: Joshua S
authors.initials: JS
authors.lastname: Yuan
authors.forename: Xiaohan
authors.initials: X
authors.lastname: Yang
authors.forename: Jingru
authors.initials: J
authors.lastname: Lai
authors.forename: Hong
authors.initials: H
authors.lastname: Lin
authors.forename: Zong-Ming
authors.initials: ZM
authors.lastname: Cheng
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Nonogaki
authors.forename: Feng
authors.initials: F
authors.lastname: Chen
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics*; D008361:Mannosidases / Q000235:genetics*; D008969:Molecular Sequence Data; D005810:Multigene Family / Q000235:genetics*; D012275:Oryza / Q000201:enzymology* / Q000235:genetics*; D032107:Populus / Q000201:enzymology* / Q000235:genetics*
chemical_list: D008361:Mannosidases; C119276:endo-beta-mannosidase