title: Characterization of Arabidopsis CTP:3-deoxy-D-manno-2-octulosonate cytidylyltransferase (CMP-KDO synthetase), the enzyme that activates KDO during rhamnogalacturonan II biosynthesis.
abstract: In plant cells, boron (B) occurs predominantly as a borate ester associated with rhamnogalacturonan II (RG-II), but the function of this B-RG-II complex has yet to be investigated. 3-Deoxy-D-manno-2-octulosonic acid (KDO) is a specific component monosaccharide of RG-II. Mutant plants defective in KDO biosynthesis are expected to have altered RG-II structure, and would be useful for studying the physiological function of the B-RG-II complex. Here, we characterized Arabidopsis CTP:KDO cytidylyltransferase (CMP-KDO synthetase; CKS), the enzyme activating KDO as a nucleotide sugar prior to its incorporation into RG-II. Our analyses localized the Arabidopsis CKS protein to mitochondria. The Arabidopsis CKS gene occurs as a single-copy gene in the genome, and we could not obtain cks null mutants from T-DNA insertion lines. Analysis using +/cks heterozygotes in the quartet1 background demonstrated that the cks mutation rendered pollen infertile through the inhibition of pollen tube elongation. These results suggest that KDO is an indispensable component of RG-II, and that the complete B-RG-II complex is essential for the cell wall integrity of rapidly growing tissues.
authors: Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan. kobayashi.masaru.8e@kyoto-u.ac.jp
authors: Masaru
authors: M
authors: Kobayashi
authors: Nagisa
authors: N
authors: Kouzu
authors: Akina
authors: A
authors: Inami
authors: Kiminori
authors: K
authors: Toyooka
authors: Yuki
authors: Y
authors: Konishi
authors: Ken
authors: K
authors: Matsuoka
authors: Toru
authors: T
authors: Matoh
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000166:cytology / Q000201:enzymology* / Q000648:ultrastructure; D020090:Chromosome Segregation / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics; D005838:Genotype; D055993:Germ Cells, Plant / Q000378:metabolism; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional / Q000235:genetics; D009154:Mutation / Q000235:genetics; D009713:Nucleotidyltransferases / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D010368:Pectins / Q000096:biosynthesis*; D053205:Pollen Tube / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D021381:Protein Transport; D011994:Recombinant Proteins / Q000378:metabolism; D016415:Sequence Alignment; D013347:Subcellular Fractions / Q000201:enzymology; D013400:Sugar Acids / Q000378:metabolism*
chemical_list: D018744:DNA, Plant; D011994:Recombinant Proteins; D013400:Sugar Acids; C042492:rhamnogalacturonan II; D010368:Pectins; D009713:Nucleotidyltransferases; C028984:3-deoxy-manno-octulosonate cytidyltransferase; C120356:3-deoxy-manno-oct-2-ulopyranosonic acid