Based on the nucleotide (nt) sequences of cob and L(2a), two oligodeoxyribonucleotides (oligos) were synthesized and used in the polymerase chain reaction (PCR) to amplify the termini of the ...Chlamydomonas reinhardtii mitochondrial (mt) genome. A 0.8-kb PCR product was detected by agarose-gel electrophoresis when using unligated mt DNA as the template for PCR. This may have indicated the presence of a naturally occurring circular mt DNA molecule that acted as the PCR template. The 0.8-kb DNA could also be amplified from the linear mt DNA via an intramolecular jump during PCR. The sequence data from the 0.8-kb PCR product, and the right 0.6-kb and left 1-kb terminal fragments of the linear mt DNA, along with Southern hybridization analysis, indicated that a 0.49-kb inverted repeat (IR) sequence is present at the right and left termini of the linear mt DNA. The IR contains A+T-rich clusters, as well as numerous short direct repeats (DR) and IR, and might be involved in the recombination, replication and expression of the C. reinhardtii mt genome.
In a retrospective review, a group of seven patients were found to have a sputum culture positive for Hafnia alvei. Hafnia alvei is a Gram-negative enteric and oropharyngeal bacillus and usually is ...nonpathogenic. All our patients had a chronic underlying illness and one of the patients was endotracheally intubated at the time of the isolation of this organism. Six of seven patients had other organisms isolated along with H alvei, and only one patient had a pure growth of H alvei confirmed by a culture obtained from a bronchoscopic protected brush specimen. All isolates displayed resistance to conventional antibiotics including cephalosporins and penicillins. Although rare, H alvei may be a potential pathogen in a patient with a chronic underlying illness.
The yeast TRP3 gene encodes a bifunctional protein with anthranilate synthase II and indoleglycerol‐phosphate synthase activities. Replacing ten consecutive non‐preferred codons in the ...indoleglycerol‐phosphate synthase region of the TRP3 gene with synonymous preferred codons (to create the TRP3pr gene; translational pause replaced) causes a 1.5‐fold reduction in relative indoleglycerol‐phosphate synthase activity Crombie, T., Swaffield, J. C. & Brown, A. J. P. (1992) J. Mol. Biol. 228, 7–12. Here, we report that both the anthranilate synthase II and indoleglycerol‐phosphate synthase domains are affected to similar extents when the translational pause is removed. Also, structural modelling of the yeast indoleglycerol‐phosphate synthase domain against the X‐ray crystal structure of indoleglycerol‐phosphate synthase from Escherichia coli indicates that the translational pause lies in a region of structural divergence between similar structures. To probe the role of cytoplasmic heat‐shock protein 70 (Hsp70) chaperones in Trp3 protein folding, anthranilate synthase and indoleglycerol‐phosphate synthase activities were measured in ssa and ssb mutants. Neither indoleglycerol‐phosphate synthase nor anthranilate synthase were affected significantly in the ssb mutant. However, depletion of Hsp70 proteins encoded by the SSA genes led to decreased anthranilate synthase and indoleglycerol‐phosphate synthase activities from the TRP3 gene, suggesting that both domains depend to some extent upon the SSA chaperone family. The data are consistent with roles for both the translational pause and Ssa chaperones in Trp3 protein folding in vivo.
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