Mutant EF-Tu increases missense error in vitro

Summary We have studied the consequences of mutational alteration in the structure of EF-Tu on the missense errors and proofreading activity of bacterial ribosomes in vitro. Our data show that the EF-Tu Bo mutant form of EF-Tu (van der Meide et al. 1983a) is inactive in polypeptide synthesis on the ribosome, even though it binds aminoacyl-tRNA. A second mutant form, EF-Tu Ar (van der Meide et al. 1983a), is active in polypeptide synthesis but supports a much higher messense incorporation with either leucine isoacceptor 2 or leucine isoacceptor 4 in the in vitro system. Further analysis of the kinetic basis of this enhanced missense frequency revealed that the mutation responsible for the alteration in EF-Tu Ar increases the errors at both the proofreading step and the initial selection. In this respect the effect of this particular mutation is similar to the mode of action of the antibiotic kanamycin (Jelenc and Kurland 1984).     

Structural and functional diversity of EF‐hand proteins: Evolutionary perspectives

We have classified 865 sequences of EF‐hand proteins from five proteomes into 156 subfamilies. These subfamilies were put into six groups. Evolutionary relationships among subfamilies and groups were analyzed from the inferred ancestral sequence for each subfamily. CTER, CPV, and PEF groups arose from a common EF‐lobe (pair of adjacent EF‐hands). They have two or more EF‐lobes; the relative positions of their EF‐lobes differ from each other. Comparisons of the ancestral sequences and the inferred structures of the EF‐lobes of these groups indicate that the mutual positions of EF‐lobes were established soon after divergence of an EF‐lobe for each group and before the duplication and fusion of EF‐lobe gene(s). These ancestral sequences reveal that some subfamilies in low similarity and isolated groups did not evolve from the EF‐lobe precursor, even if their conformations are similar to the canonical EF‐hand. This is an example of convergent evolution.     

Molecular cloning and expression pattern of 11 genes involved in lipid metabolism in yellow catfish Pelteobagrus fulvidraco

11 genes involved in lipid metabolism were cloned from liver of yellow catfish Pelteobagrus fulvidraco, including CPT 1A, CPT 1B, PPARα, PPARγ, SREBP-1, G6PD, 6PGD, FAS, acetyl-CoA ACCa, ACCb, and LPL. Phylogenetic analysis further identified these genes, and confirmed the classification and evolutionary status of yellow catfish. mRNA of all eleven genes was present in liver, muscle, mesenteric adipose, ovary and heart, but at varying levels. The present study will facilitate further studies on the regulation of lipid metabolism at the molecular level for the fish species.     

Genetic and in silico analysis of plantaricin EFI locus in indigenous isolates of lactobacillus plantarum

Genetic investigation and in silico analysis of plantaricin EFI (plnEFI) locus was performed in three indigenous isolates of Lactobacillus plantarum EL3, L28 and BL1. Amplification with plnEFI specific primers and production of ~ 10 KDa size protein suggested the existence of class II bacteriocins. The analysis demonstrated that the studied fragment included structural bacteriocin, immunity, partial transporter and potential regulatory encoding regions. Based on the results, there was one DNA polymorphic site in plnE as well as plnF of the studied sequences. One nucleotide substitution in plnE of BL1 isolate lead to replacement of Glycin with Valine. These two are of non-polar type which did not affect instability index of plnE protein. The only nucleotide variation in plnF of EL3 isolate did not change the amino acid sequence since the modified nucleotide constituted alternative codon of the original amino acid. The highest DNA polymorphism occurred in the region with immunity function which in BL1 resulted in the conversion of start codon to amino acid codon. In the partial transporter sequence, one variable nucleotide site caused amino acid replacement in all the isolates which elevated stability of N-terminal domain in the transporter protein compared to nominated reference isolate L. plantarum C11. The region with possible regulatory function was identical in all three isolates. © 2018 American Institute of Chemical Engineers Biotechnol Progress, 35: e2773, 2019.