title: Studies of three genes encoding Cinnamomin (a type II RIP) isolated from the seeds of camphor tree and their expression patterns.
abstract: Cinnamomin, which has three isoforms, is a type II ribosome-inactivating protein (RIP) purified from the mature seeds of camphor tree (Cinnamomum camphora). In a previous study, an incomplete cDNA that encoded the A- and B-chain of Cinnamomin but lacked signal peptide sequence was cloned. In the present paper, its full-length cDNA was obtained by 5' rapid amplification of cDNA ends (5'RACE). Subsequently, polymerase chain reaction (PCR) amplification of its genomic DNA was performed. Unexpectedly, sequence analysis of the PCR products revealed three cinnamomin genes with >98.0% sequence identity. One of them corresponded to the published cDNA and was designated as cinnamomin I, whereas the other two genes were named as cinnamomin II and cinnamomin III, respectively. RT-PCR amplification of the cDNAs of cinnamomin II and III manifested that these two genes were functional. The three genes have no intron. Three Cinnamomin precursors that were inferred from the cDNA sequence of three cinnamomin genes exhibited relatively high sequence homology with other type II RIPs. Northern blot analysis demonstrated that the cinnamomin genes only expressed in cotyledons of C. camphora seeds and the acmes of expression emerged at 75-90 DAF when seeds were close to maturity. It is proposed that the three cinnamomin genes may encode three isoforms of Cinnamomin. The physiological function of Cinnamomin in C. camphora seeds is briefly discussed.
authors.affiliation: State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences. 320 Yue-Yang Road, Shanghai 200031, China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Yang
authors.forename: Ren-shui
authors.initials: RS
authors.lastname: Liu
authors.forename: Zhen-zhen
authors.initials: ZZ
authors.lastname: Gong
authors.forename: Wang-Yi
authors.initials: WY
authors.lastname: Liu
mesh_terms: D020418:Algal Proteins; D000595:Amino Acid Sequence; D001483:Base Sequence; D027423:Cinnamomum camphora / Q000235:genetics*; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D018744:DNA, Plant / Q000737:chemistry / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D008969:Molecular Sequence Data; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics*; D020033:Protein Isoforms / Q000235:genetics / Q000302:isolation & purification; D011506:Proteins / Q000235:genetics* / Q000302:isolation & purification; D054790:Ribosome Inactivating Proteins, Type 2; D012639:Seeds / Q000235:genetics*; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid
chemical_list: D020418:Algal Proteins; D018076:DNA, Complementary; D018744:DNA, Plant; D010940:Plant Proteins; D020033:Protein Isoforms; D011506:Proteins; D054790:Ribosome Inactivating Proteins, Type 2; C061930:cinnamomin, Phytophthora cinnamomi