Molecular evolution of the avian growth hormone gene and comparison with its mammalian counterpart

Buggiotti, Laura; Primmer, Craig R.

doi:10.1111/j.1420-9101.2005.01042.x

Cited by 12 publications

(6 citation statements)

References 61 publications

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“…In many cases, the Ka/Ks values of signal peptides were found to be 2–7 times higher than those of the mature proteins. Similar results for an increased rate of evolution of signal peptides were reported for yeast [48] and avian growth hormone genes [49]. Although there might be a tendency, we failed to find a strong correlation between Ka/Ks values of the mature and signal peptides.…”

Section: Resultssupporting

confidence: 82%

Contrasted evolutionary constraints on secreted and non-secreted proteomes of selected Actinobacteria

et al. 2013

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BackgroundActinobacteria have adapted to contrasted ecological niches such as the soil, and among others to plants or animals as pathogens or symbionts. Mycobacterium genus contains mostly pathogens that cause a variety of mammalian diseases, among which the well-known leprosy and tuberculosis, it also has saprophytic relatives. Streptomyces genus is mostly a soil microbe known for its secondary metabolites, it contains also plant pathogens, animal pathogens and symbionts. Frankia, a nitrogen-fixing actinobacterium establishes a root symbiosis with dicotyledonous pionneer plants. Pathogens and symbionts live inside eukaryotic cells and tissues and interact with their cellular environment through secreted proteins and effectors transported through transmembrane systems; nevertheless they also need to avoid triggering host defense reactions. A comparative genome analysis of the secretomes of symbionts and pathogens allows a thorough investigation of selective pressures shaping their evolution. In the present study, the rates of silent mutations to non-silent mutations in secretory proteins were assessed in different strains of Frankia, Streptomyces and Mycobacterium, of which several genomes have recently become publicly available.ResultsIt was found that secreted proteins as a whole have a stronger purifying evolutionary rate (non-synonymous to synonymous substitutions or Ka/Ks ratio) than the non-secretory proteins in most of the studied genomes. This difference becomes statistically significant in cases involving obligate symbionts and pathogens. Amongst the Frankia, secretomes of symbiotic strains were found to have undergone evolutionary trends different from those of the mainly saprophytic strains. Even within the secretory proteins, the signal peptide part has a higher Ka/Ks ratio than the mature part. Two contrasting trends were noticed amongst the Frankia genomes regarding the relation between selection strength (i.e. Ka/Ks ratio) and the codon adaptation index (CAI), a predictor of the expression rate, in all the genes belonging to the core genome as well as the core secretory protein genes. The genomes of pathogenic Mycobacterium and Streptomyces also had reduced secretomes relative to saprophytes, as well as in general significant pairwise Ka/Ks ratios in their secretomes.ConclusionIn marginally free-living facultative symbionts or pathogenic organisms under consideration, secretory protein genes as a whole evolve at a faster rate than the rest and this process may be an adaptive life-strategy to counter the host selection pressure. The higher evolutionary rate of signal peptide part compared to mature protein provides an indication that signal peptide parts may be under relaxed purifying selection, indicative of the signal peptides not being secreted into host cells. Codon usage analysis suggests that in actinobacterial strains under host selection pressure such as symbiotic Frankia, ACN, FD and the pathogenic Mycobacterium, codon usage bias was negatively correlated to the selective pressure exerted o...

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Section: Resultssupporting

confidence: 82%

Contrasted evolutionary constraints on secreted and non-secreted proteomes of selected Actinobacteria

et al. 2013

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“…The paralogs appear to have functionally diverged, but only one of the paralogs shows evidence for positive selection. Buggiotti and Primmer (2006) pointed out that, of the 6 avian taxa they studied, the most divergent GH amino acid sequence was that of a passerine bird, European pied flycatcher (Ficedula hypoleuca), which differed from the other avian GH polypeptides by 18-27 amino acids, whereas divergence among the other 5 taxa ranged from 2 to 22 amino acids. This level of amino acid sequence divergence is comparable to that found between the green sea turtle (Chelonia mydas) and avian GH polypeptides (23-29 amino acid divergence).…”

Section: Discussionmentioning

confidence: 99%

Duplication of Accelerated Evolution and Growth Hormone Gene in Passerine Birds

Yuri

Kimball

Braun

et al. 2007

Molecular Biology and Evolution

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We report the discovery of a duplication of the growth hormone (GH) gene in a major group of birds, the passerines (Aves: Passeriformes). Phylogenetic analysis of 1.3-kb partial DNA sequences of GH genes for 24 species of passerines and numerous outgroups indicates that the duplication occurred in the ancestral lineage of extant passerines. Both duplicates and their open-reading frames are preserved throughout the passerine clade, and both duplicates are expressed in the zebra finch brain, suggesting that both are likely to be functional. The estimated rates of amino acid evolution are more than 10-fold higher in passerine GH genes than in those of their closest nonpasserine relatives. In addition, although the 84 codons sequenced are generally highly conserved for both passerines and nonpasserines, comparisons of the nonsynonymous/synonymous substitution ratios and the rate of predicted amino acid changes indicate that the 2 gene duplicates are evolving under different selective pressures and may be functionally divergent. The evidence of differential selection, coupled with the preservation of both gene copies in all major lineages since the origin of passerines, suggests that the duplication may be of adaptive significance, with possible implications for the explosive diversification of the passerine clade.

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“…This phenomenon has also been observed in different genes from previous studies. For example, the signal peptides of avian growth hormone genes diverged rapidly (Buggiotti and Primmer, 2006), but those of murine β-defensin gene family are highly conserved (Morrison et al, 2003). This could be due to the small size of signal peptides, which may provide misleading estimates (Li et al, 1985).…”

Section: Signal Peptides Evolve Faster Than Mature Regionsmentioning

confidence: 97%

“…They proposed that this rapid evolution should not be neutral, with some amino acid substitutions affected by natural selection (Williams et al, 2000;Buggiotti and Primmer, 2006). For example, the C-region always contains small and neutral residues at −3 and −1 position (i.e., AXA), which are recognized by membrane-bound signal peptidases.…”

Section: Introductionmentioning

confidence: 99%

The rapid evolution of signal peptides is mainly caused by relaxed selection on non-synonymous and synonymous sites

Xie

et al. 2009

Gene

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Molecular evolution of the avian growth hormone gene and comparison with its mammalian counterpart

Cited by 12 publications

References 61 publications

Contrasted evolutionary constraints on secreted and non-secreted proteomes of selected Actinobacteria

Contrasted evolutionary constraints on secreted and non-secreted proteomes of selected Actinobacteria

Duplication of Accelerated Evolution and Growth Hormone Gene in Passerine Birds

The rapid evolution of signal peptides is mainly caused by relaxed selection on non-synonymous and synonymous sites

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