Significance of codon usage and irregularities of rare codon distribution in genes for expression of BspLU11III methyltransferases.
Genes of adenine-specific DNA-methyltransferase M.BspLU11IIIa and cytosine-specific DNA-methyltransferase M.BspLU11IIIb of the type IIG BspLU11III restriction-modification system from the thermophilic strain Bacillus sp. LU11 were expressed in E. coli. They contain a large number of codons that are rare in E. coli and are characterized by equal values of codon adaptation index (CAI) and expression level measure (E(g)). Rare codons are either diffused (M.BspLU11IIIa) or located in clusters (M.BspLU11IIIb). The expression level of the cytosine-specific DNA-methyltransferase was increased by a factor of 7.3 and that of adenine-specific DNA only by a factor of 1.25 after introduction of the plasmid pRARE supplying tRNA genes for six rare codons in E. coli. It can be assumed that the plasmid supplying minor tRNAs can strongly increase the expression level of only genes with cluster distribution of rare codons. Using heparin-Sepharose and phosphocellulose chromatography and gel filtration on Sephadex G-75 both DNA-methyltransferases were isolated as electrophoretically homogeneous proteins (according to the results of SDS-PAGE).
Kirienko
N V
NV
Institute of Protein Research, Russian Academy of Sciences, Pushchino, 142290, Moscow Region, Russia. nikmatv@vega.protres.ru
Lepikhov
K A
KA
Zheleznaya
L A
LA
Matvienko
N I
NI
D000595:Amino Acid Sequence; D001407:Bacillus / Q000201:enzymology; D002850:Chromatography, Gel; D003062:Codon / Q000235:genetics*; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000096:biosynthesis* / Q000302:isolation & purification; D015280:DNA Restriction-Modification Enzymes / Q000235:genetics*; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D015971:Gene Expression Regulation, Enzymologic; D008969:Molecular Sequence Data; D010957:Plasmids / Q000235:genetics; D016133:Polymerase Chain Reaction; D011994:Recombinant Proteins / Q000096:biosynthesis; D015265:Site-Specific DNA-Methyltransferase (Adenine-Specific) / Q000096:biosynthesis* / Q000302:isolation & purification
D003062:Codon; D015280:DNA Restriction-Modification Enzymes; D011994:Recombinant Proteins; D004248:DNA (Cytosine-5-)-Methyltransferases; D015265:Site-Specific DNA-Methyltransferase (Adenine-Specific); C092321:endodeoxyribonuclease BspLU11III