scholarly journals Metal transporter encoding gene families in Fabaceae: II. Cation/H+ exchanger (CAX) encoding genes

Author(s):  
Bang Phi Cao ◽  
Anh Thi Van Le

The plant CAtion/H+ eXchangers (CAX) proteins belong to Ca2+/cation antiporter (CaCA) superfamily. By using in silico methods, the CAX encoding genes in the genome of six legume species have been identified in this work. In examined legume genomes, the CAX genes belong to a small multigenic family. The number of the CAX genes in these legume species is 17 (soybean), 6 (common bean and C. cajan), 5 (M. truncatula and C. arietinum) and 3 genes (L. japonicus), respectively. The legume CAX genes vary in genomic full-length ranging from 1,213 to 11,561 base pairs. All of the genes exhibit introns (from 4 to 11 introns). Their deduced full-length protein sequences range from 248 to 718 amino acids. Theoretical pI values of most (39/42) of legume CAX proteins were less than 7. The secondary structure modelling of protein exhibit transmembrane helix region (from 3 to 11 regions). Half of all (23/42) included 11 transmembrane helix regions. Based on phylogeny analysis, all of the legume CAX were divided into two groups, A and B, each consisting of two subgroups. The phylogeny suggested an ancient gene duplication in the genome of legumes ancestry. The recent gene duplication even was only detected in the soybean genome after the speciation. The expression analysis showed that all of 3 L. japonicus CAX genes expressed in all examined tissues. However, the expression of C. cajan CAX genes was not detected. For each of 4 remaining legumes, the CAX genes were differed in their expression level depending on studied tissues. The tissue-specific expressions of some CAX genes were observed in 5 out of the 6 legume species, except C. cajan.

Author(s):  
Cao Phi Bằng

In plants, Zinc and Iron are transported through the membrane by proteins belonging to Zinc-Iron permease (ZIP: ZRT/IRT-like Protein). In this work, the ZIP gene families were identified in the genome of five legume species. The results demonstrated that the ZIPs were belonged to a multigeneic family in each species including soybean (28 genes), Medicago truncalata (16 genes), chickpea (7 genes), pigeon pea (12 genes), and Lotus japonicus (15 genes). Each gene contained from one to twelve introns. ZIP proteins possessed a conserved histidine-rich motif. Most of these proteins contained eight putative transmembrane domains and were predicted to be localized in plasma membranes. The phylogeny analysis showed that the legume ZIPs were classified into four main groups, each of which includes many subgroups. The group I contained the ZIP members of five examined plants. Moreover, the phylogeny showed gene gain events (expansion) in group I and gene loss events in other groups. The gene expansion in group I is likely to have arisen mainly from recent duplication events of ZIP genes in the examined legume plants, after specialization. The expression analysis showed that all of ZIP genes were expressed in all of the examined tissues in L. japonicus. The expression level of ZIP members was not similar in different tissues of the plant. Some ZIP genes were predominantly expressed in certain tissues for most of the legume species investigated.


1984 ◽  
Vol 4 (12) ◽  
pp. 2661-2667
Author(s):  
D Dawson ◽  
G Herrick

Approximately 20,000 different short, linear, macronuclear DNA molecules are derived from micronuclear sequences of Oxytricha fallax after conjugation. These macronuclear DNAs are terminated at both ends by 20 base pairs of the sequence 5'-dC4A4-3'. Sequences homologous to this repeat (C4A4+) are also abundant in the micronuclear chromosomes, but most reside at their telomeres. Here we show that nontelomeric C4A4 clusters of 20 base pairs or longer exist in only a few hundred copies per micronuclear genome. This demonstrates that nearly none of the 20,000 sequence blocks of micronuclear DNA destined to be macronuclear DNA molecules can be flanked by full-length (20-base pair) C4A4 clusters, and therefore C4A4 repeats must be added to most, if not all, macronuclear telomeres during macronuclear development. Six internal micronuclear C4A4+ loci were cloned, and their structural relationships with macronuclear and micronuclear sequences were examined. The possible origins and functions of these rare, micronuclear internal C4A4 loci are discussed.


1987 ◽  
Vol 7 (4) ◽  
pp. 1559-1562
Author(s):  
J Silver ◽  
A Rabson ◽  
T Bryan ◽  
R Willey ◽  
M A Martin

Novel endogenous human retroviral sequences were cloned by low-stringency hybridization, using the pol gene of endogenous human retrovirus 51-1. One clone, lambda NP-2, contained gag, pol, env, and long terminal repeat sequences related to the corresponding portions of clone 51-1 and the closely related full-length endogenous human retrovirus 4-1. The sequence of the env gene of NP-2 was 73% homologous to that of 4-1. Genomic Southern blots of male and female DNAs showed that NP-2 is located on the Y chromosome and that the Y chromosome also contains one other sequence closely related to the env and 3' flanking regions of NP-2. Conservation of flanking DNA suggests that the second Y chromosome copy of the NP-2 env sequence arose by gene duplication rather than provirus insertion.


2018 ◽  
Vol 115 (33) ◽  
pp. 8364-8369 ◽  
Author(s):  
Edward Tunnacliffe ◽  
Adam M. Corrigan ◽  
Jonathan R. Chubb

During the evolution of gene families, functional diversification of proteins often follows gene duplication. However, many gene families expand while preserving protein sequence. Why do cells maintain multiple copies of the same gene? Here we have addressed this question for an actin family with 17 genes encoding an identical protein. The genes have divergent flanking regions and are scattered throughout the genome. Surprisingly, almost the entire family showed similar developmental expression profiles, with their expression also strongly coupled in single cells. Using live cell imaging, we show that differences in gene expression were apparent over shorter timescales, with family members displaying different transcriptional bursting dynamics. Strong “bursty” behaviors contrasted steady, more continuous activity, indicating different regulatory inputs to individual actin genes. To determine the sources of these different dynamic behaviors, we reciprocally exchanged the upstream regulatory regions of gene family members. This revealed that dynamic transcriptional behavior is directly instructed by upstream sequence, rather than features specific to genomic context. A residual minor contribution of genomic context modulates the gene OFF rate. Our data suggest promoter diversification following gene duplication could expand the range of stimuli that regulate the expression of essential genes. These observations contextualize the significance of transcriptional bursting.


2001 ◽  
Vol 11 (5) ◽  
pp. 771-780 ◽  
Author(s):  
Austin L. Hughes ◽  
Jack da Silva ◽  
Robert Friedman

The fact that there are four homeobox (Hox) clusters in most vertebrates but only one in invertebrates is often cited as evidence for the hypothesis that two rounds of genome duplication by polyploidization occurred early in vertebrate history. In addition, it has been observed in humans and other mammals that numerous gene families include paralogs on two or more of the fourHox-bearing chromosomes (the chromosomes bearing theHox clusters; i.e., human chromosomes 2, 7, 12, and 17), and the existence of these paralogs has been taken as evidence that these genes were duplicated along with the Hox clusters by polyploidization. We tested this hypothesis by phylogenetic analysis of 42 gene families including members on two or more of the humanHox-bearing chromosomes. In 32 of these families there was evidence against the hypothesis that gene duplication occurred simultaneously with duplication of the Hox clusters. Phylogenies of 14 families supported the occurrence of one or more gene duplications before the origin of vertebrates, and of 15 gene duplication times estimated for gene families evolving in a clock-like manner, only six were dated to the same time period early in vertebrate history during which the Hox clusters duplicated. Furthermore, of gene families duplicated around the same time as the Hoxclusters, the majority showed topologies inconsistent with their having duplicated simultaneously with the Hox clusters. The results thus indicate that ancient events of genome duplication, if they occurred at all, did not play an important role in structuring the mammalian Hox-bearing chromosomes.


1987 ◽  
Vol 7 (4) ◽  
pp. 1559-1562 ◽  
Author(s):  
J Silver ◽  
A Rabson ◽  
T Bryan ◽  
R Willey ◽  
M A Martin

Novel endogenous human retroviral sequences were cloned by low-stringency hybridization, using the pol gene of endogenous human retrovirus 51-1. One clone, lambda NP-2, contained gag, pol, env, and long terminal repeat sequences related to the corresponding portions of clone 51-1 and the closely related full-length endogenous human retrovirus 4-1. The sequence of the env gene of NP-2 was 73% homologous to that of 4-1. Genomic Southern blots of male and female DNAs showed that NP-2 is located on the Y chromosome and that the Y chromosome also contains one other sequence closely related to the env and 3' flanking regions of NP-2. Conservation of flanking DNA suggests that the second Y chromosome copy of the NP-2 env sequence arose by gene duplication rather than provirus insertion.


2016 ◽  
Vol 113 (35) ◽  
pp. E5125-E5134 ◽  
Author(s):  
Yaqiang Wang ◽  
Joseph D. Yesselman ◽  
Qi Zhang ◽  
Mijeong Kang ◽  
Juli Feigon

Telomerase is an RNA–protein complex that includes a unique reverse transcriptase that catalyzes the addition of single-stranded telomere DNA repeats onto the 3′ ends of linear chromosomes using an integral telomerase RNA (TR) template. Vertebrate TR contains the template/pseudoknot (t/PK) and CR4/5 domains required for telomerase activity in vitro. All vertebrate pseudoknots include two subdomains: P2ab (helices P2a and P2b with a 5/6-nt internal loop) and the minimal pseudoknot (P2b–P3 and associated loops). A helical extension of P2a, P2a.1, is specific to mammalian TR. Using NMR, we investigated the structures of the full-length TR pseudoknot and isolated subdomains in Oryzias latipes (Japanese medaka fish), which has the smallest vertebrate TR identified to date. We determined the solution NMR structure and studied the dynamics of medaka P2ab, and identified all base pairs and tertiary interactions in the minimal pseudoknot. Despite differences in length and sequence, the structure of medaka P2ab is more similar to human P2ab than predicted, and the medaka minimal pseudoknot has the same tertiary interactions as the human pseudoknot. Significantly, although P2a.1 is not predicted to form in teleost fish, we find that it forms in the full-length pseudoknot via an unexpected hairpin. Model structures of the subdomains are combined to generate a model of t/PK. These results provide evidence that the architecture for the vertebrate t/PK is conserved from teleost fish to human. The organization of the t/PK on telomerase reverse transcriptase for medaka and human is modeled based on the cryoEM structure of Tetrahymena telomerase, providing insight into function.


2020 ◽  
Author(s):  
Samuel Hermann Alexander Von Der Dunk ◽  
Berend Snel

Abstract Background Convergent and parallel evolution provide unique insights into the mechanisms of natural selection. Some of the most striking convergent and parallel (collectively recurrent ) amino acid substitutions in proteins are adaptive, but there are also many that are selectively neutral. Accordingly, genome-wide assessment has shown that recurrent sequence evolution in orthologs is chiefly explained by nearly neutral evolution. For paralogs, more frequent functional change is expected because additional copies are generally not retained if they do not acquire their own niche. Yet, it is unknown to what extent recurrent sequence differentiation is discernible after independent gene duplications in different eukaryotic taxa. Results We develop a framework that detects patterns of recurrent sequence evolution in duplicated genes. This is used to analyze the genomes of 90 diverse eukaryotes. We find a remarkable number of families with a potentially predictable functional differentiation following gene duplication. In some protein families, more than ten independent duplications show a similar sequence-level differentiation between paralogs. Based on further analysis, the sequence divergence is found to be generally asymmetric. Moreover, about 6\% of the recurrent sequence evolution between paralog pairs can be attributed to recurrent differentiation of subcellular localization. Finally, we reveal the specific recurrent patterns for the gene families Hint1/Hint2, Sco1/Sco2 and vma11/vma3. Conclusions The presented methodology provides a means to study the biochemical underpinning of functional differentiation between paralogs. For instance, two abundantly repeated substitutions are identified between independently derived Sco1 and Sco2 paralogs. Such identified substitutions allow direct experimental testing of the biological role of these residues for the repeated functional differentiation. We also uncover a diverse set of families with recurrent sequence evolution and reveal trends in the functional and evolutionary trajectories of this hitherto understudied phenomenon.


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