Plastid genome structure and evolution: Operons, novel genes and inteins.
| dc.contributor.author | Wang, Shenglong. | en_US |
| dc.contributor.degree | Ph.D. | en_US |
| dc.date.accessioned | 2014-10-21T12:38:29Z | |
| dc.date.available | 1996 | |
| dc.date.issued | 1996 | en_US |
| dc.description | Plastid genome structure and evolution were studied by analyzing a cryptomonad plastid believed to have originated through secondary endosymbiosis. Sequence determination of a 14-kbp DNA fragment from the Guillardia theta plastid genome revealed 12 genes. The arrangement of these genes is acpA-hlpA-dnaK-rpl3-rpl4-rpl23-rpl2-rps19-rpl22-rps3-rpl1 6-rpl29-rps17-rpl14-rpl24-rpl5-rps8-rpl6-rpl18-rps5-secY-rpl36. The acpA, HlpA and dnaK genes encode, respectively, an acyl carrier protein, a histone-like protein, and an Hsp70 family protein. All three genes were found for the first time in a cell organelle genome, and each gene represented a functional class of plastid genes not previously described. The downstream genes are ribosomal protein genes (except secY), and their organization resembles the two largest and adjacent ribosomal protein operons (S10 and spc) of E. coli. An RNA transcript of 10,000 nucleotide long was detected for these ribosomal protein genes, further suggesting that they are expressed as an operon. When compared to corresponding operons (or gene clusters) in plastid genomes of other organisms, this Guillardia theta plastid ribosomal protein operon has retained the largest number of genes. Relative to corresponding ribosomal protein operons (str-S10-spc-alpha) in E.coli, the Guillardia theta plastid operons appear to have undergone rearrangement, expansion, and fusion in forming a much larger ribosomal protein operon. | en_US |
| dc.description | The expression and protein products of two structurally unusual Chlamydomonas chloroplast genes were investigated for possible presence of inteins and protein splicing. They are the rps3 gene encoding a ribosomal protein (Rps3) and the clpP gene encoding a protease protein (ClpP), with both genes containing large translated insertion sequences. For the ClpP protein, it was demonstrated that one of its insertion sequence, IS2, is a degenerate intein that can be restored to protein splicing by a single amino acid substitution. The other large insertion sequence in the ClpP protein, IS1, was not excised from the precursor protein either in vitro or in vivo under conditions studied, indicating that it is not an intein. Similarly, an insertion sequence in the Rps3 protein does not appear to be an intein. Instead, the Rps3 precursor protein appears to be cleaved into smaller protein products, all of which are assembled into the ribosomal small subunit. The IS2 sequence of the ClpP protein thus represents the first, and sor the only, intein found in an organelle genome, while the ClpP protein represents the fourth functionally distinctive protein found to contain an intein. | en_US |
| dc.description | Thesis (Ph.D.)--Dalhousie University (Canada), 1996. | en_US |
| dc.identifier.other | AAINN16026 | en_US |
| dc.identifier.uri | http://hdl.handle.net/10222/55159 | |
| dc.language | eng | en_US |
| dc.publisher | Dalhousie University | en_US |
| dc.publisher | en_US | |
| dc.subject | Biology, Molecular. | en_US |
| dc.subject | Chemistry, Biochemistry. | en_US |
| dc.title | Plastid genome structure and evolution: Operons, novel genes and inteins. | en_US |
| dc.type | text | en_US |
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