Functional genomic analysis of Arabidopsis thaliana glycoside hydrolase family 35.
Catalysing the hydrolysis of terminal beta-galactosyl residues from carbohydrates, galactolipids, and glycoproteins, glycoside hydrolase family 35 (beta-galactosidases; BGALs) are widely distributed in plants and believed to play many key roles, including modification of cell wall components. Completion of the Arabidopsis thaliana genome sequencing project has, for the first time, allowed an examination of the total number, gene structure, and evolutionary patterns of all Family 35 members in a representative (model) angiosperm. Reiterative database searches established a multigene family of 17 members (designated BGAL1-BGAL17). Using these genes as query sequences, BLAST and Hidden Markov Model searches identified BGAL genes among 22 other eukaryotes, whose genomic sequences are known. The Arabidopsis (n=17) and rice (n=15) BGAL families were much larger than those of Chlamydomonas, fungi, and animals (n=0-4), and a lineage-specific expansion of BGAL genes apparently occurred after divergence of the Arabidopsis and rice lineages. All plant BGAL genes, with the exception of Arabidopsis BGAL17 and rice Os 9633.m04334, form a monophyletic group. Arabidopsis BGAL expression levels are much higher in mature leaves, roots, flowers, and siliques but are lower in young seedlings. BGAL8, BGAL11, BGAL13, BGAL14, and BGAL16 are expressed only in flowers. Catalytically active BGAL4 was produced in the E. coli and baculoviral expression systems, purified to electrophoretic homogeneity, and partially characterized. The purified enzyme hydrolyzed p- and o-nitrophenyl-beta-d-galactosides. It also cleaved beta-(1,3)-, beta-(1,4)-, and beta-(1,6)-linked galactobiosides and galactotriosides, showing a marked preference for beta-(1,3)- and beta-(1,4)-linkages.
Ahn
Young Ock
YO
Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA.
Zheng
Meiying
M
Bevan
David R
DR
Esen
Asim
A
Shiu
Shin-Han
SH
Benson
Jonas
J
Peng
Hsiao-Ping
HP
Miller
Joseph T
JT
Cheng
Chi-Lien
CL
Poulton
Jonathan E
JE
Shih
Ming-Che
MC
D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000145:classification / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D004926:Escherichia coli / Q000235:genetics; D019143:Evolution, Molecular; D018745:Genome, Plant; D023281:Genomics; D008969:Molecular Sequence Data; D005810:Multigene Family; D010802:Phylogeny; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D001616:beta-Galactosidase / Q000145:classification / Q000235:genetics* / Q000378:metabolism / Q000502:physiology
D029681:Arabidopsis Proteins; D011994:Recombinant Proteins; C522583:BGAL4 protein, Arabidopsis; D001616:beta-Galactosidase