| mutations affecting translational coupling between the rep genes of an incb miniplasmid. | the nature of translational coupling between repb and repa, the overlapping rep genes of the incb plasmid pmu720, was examined. mutations in the start codon of the promoter proximal gene, repb, reduced the efficiency of translation of both rep genes. moreover, there was no independent initiation of repa translation in the absence of repb translation. the position of the repb stop codon was crucial for the efficient expression of repa, with the wild-type positioning being optimal. translational c ... | 1992 | 1372603 |
| molecular analysis of rnai control of repb translation in incb plasmids. | the translation of repa, the replication initiation protein of the incb plasmid pmu720, requires that its mrna (rnaii) folds to form a pseudoknot immediately upstream of the repa shine-dalgarno sequence. the formation of this pseudoknot is dependent in turn on the translation and correct termination of a leader peptide, repb. a small countertranscript rna, rnai, controls the replication of pmu720 by interacting with rnaii to negatively regulate the expression of repa both directly, by sequesteri ... | 1994 | 7525535 |
| role of cis in replication of an incb plasmid. | replication of the incb plasmid pmu720 requires the synthesis of the cis-acting repa protein and the presence of two dna elements, ori and cis. cis is the 166-bp sequence separating the repa coding sequence from ori. to investigate how this organization of the pmu720 replicon contributes to the mechanism of initiation of replication, mutations in the sequence and/or the length of cis were introduced into the cis region and their effects on the efficiency of replication of the pmu720 replicon in ... | 1999 | 10217766 |
| effect of cis on activity in trans of the replication initiator protein of an incb plasmid. | repa, the replication initiator protein of the incb plasmid pmu720, acts preferentially in cis. the cis activity of repa is thought to be mediated by cis, a 166-bp region of dna separating the coding region of repa from the origin of replication (ori) of pmu720. to investigate the trans activity of repa, the repa gene, without its cognate ori, was cloned on a multicopy plasmid, psu39. the ori on which repa acts was cloned on pam34, a plasmid whose replicon is inactive without induction by isopro ... | 2000 | 10869075 |
| pseudoknot-dependent translational coupling in repba genes of the incb plasmid pmu720 involves reinitiation. | replication of the incb miniplasmid pmu720 requires synthesis of the replication initiator protein, repa, whose translation is coupled to that of a leader peptide, repb. the unusual feature of this system is that translational coupling in repba has to be activated by the formation of a pseudoknot immediately upstream of the repa shine-dalgarno sequence. a small antisense rna, rnai, controls replication of pmu720 by interacting with repba mrna to inhibit expression of repa both directly, by preve ... | 2002 | 12270836 |
| interaction of the initiator protein of an incb plasmid with its origin of dna replication. | the replication initiator protein repa of the incb plasmid pmu720 was purified and used in dnase i protection assays in vitro. repa protected a 68-bp region of the origin of replication of pmu720. this region, which lies immediately downstream of the dnaa box, contains four copies of the sequence motif 5'aancngcaa3'. mutational analyses identified this sequence as the binding site specifically recognized by repa (the repa box). binding of repa to the repa boxes was ordered and sequential, with t ... | 2003 | 12644491 |
| role of repa and dnaa proteins in the opening of the origin of dna replication of an incb plasmid. | the replication initiator protein repa of the incb plasmid pmu720 was shown to induce localized unwinding of its cognate origin of replication in vitro. dnaa, the initiator protein of escherichia coli, was unable to induce localized unwinding of this origin of replication on its own but enhanced the opening generated by repa. the opened region lies immediately downstream of the last of the three binding sites for repa (repa boxes) and covers one turn of dna helix. a 6-mer sequence, 5'-tcttaa-3', ... | 2004 | 15175292 |