Neutral Evolution of the Sex-Determining Gene transformer in Drosophila

Genetics ◽  
2000 ◽  
Vol 154 (4) ◽  
pp. 1711-1720 ◽  
Author(s):  
Bryant F McAllister ◽  
Gilean A T McVean
Keyword(s):  
Amino Acid ◽  
Amino Acid Sequence ◽  
Sequence Variation ◽  
Nonsynonymous Substitution ◽  
Neutral Evolution ◽  
Sequence Evolution ◽  
Statistical Support ◽  
Rapid Pace ◽  
Elevated Rate ◽  
Evolution Sequence

Abstract The amino acid sequence of the transformer (tra) gene exhibits an extremely rapid rate of evolution among Drosophila species, although the gene performs a critical step in sex determination. These changes in amino acid sequence are the result of either natural selection or neutral evolution. To differentiate between selective and neutral causes of this evolutionary change, analyses of both intraspecific and interspecific patterns of molecular evolution of tra gene sequences are presented. Sequences of 31 tra alleles were obtained from Drosophila americana. Many replacement and silent nucleotide variants are present among the alleles; however, the distribution of this sequence variation is consistent with neutral evolution. Sequence evolution was also examined among six species representative of the genus Drosophila. For most lineages and most regions of the gene, both silent and replacement substitutions have accumulated in a constant, clock-like manner. In exon 3 of D. virilis and D. americana we find evidence for an elevated rate of nonsynonymous substitution, but no statistical support for a greater rate of nonsynonymous relative to synonymous substitutions. Both levels of analysis of the tra sequence suggest that, although the gene is evolving at a rapid pace, these changes are neutral in function.

scholarly journals Strain-specific and common epitopes of gonococcal pili.

1984 ◽  
Vol 160 (1) ◽  
pp. 208-221 ◽  
Author(s):  
J B Rothbard ◽  
R Fernandez ◽  
G K Schoolnik
Keyword(s):  
Amino Acid ◽  
Amino Acid Sequence ◽  
Synthetic Peptides ◽  
Cyanogen Bromide ◽  
Sequence Variation ◽  
Antigenic Structure ◽  
Carboxyl Terminus ◽  
Specific Epitope ◽  
Absorption Studies ◽  
Strain Ms11

The antigenic structure of gonococcal pilin, strain MS11 (Tr), was investigated by assaying the binding of antisera engendered by intact pili from strains MS11 and R10 and their two major cyanogen bromide-generated fragments, CNBr-2 (residues 9-92) and CNBr-2 (residues 93-159), to synthetic peptides corresponding to the amino acid sequence of MS11 pilin. Four peptides were synthesized corresponding to regions of sequence variation between MS11 and R10 gonococcal pilin. Antisera against the homologous pilus filament and against its CNBr-3 fragment bind peptides equivalent to residues 121-134 and 135-151, which comprise the 30 amino acid disulfide loop near the carboxyl terminus of the protein. Heterologous pili antisera did not bind these peptides. Absorption studies proved that each peptide contained an independent, strain-specific epitope. Synthetic peptides corresponding to regions of identical sequence between MS11 and R10 pilin were used in similar binding experiments to localize a weakly immunogenic, common determinant between residues 48 and 60. less than 15% of the antibodies raised against intact pili were directed at this site. Antisera raised against MS11 or R10 CNBr-2 bind a separate peptide, residues 69-80. This region is immunogenic only as a fragment, not in the intact pilus filament.

Site interdependence attributed to tertiary structure in amino acid sequence evolution

Gene ◽  
2005 ◽  
Vol 347 (2) ◽  
pp. 207-217 ◽  
Author(s):  
Nicolas Rodrigue ◽  
Nicolas Lartillot ◽  
David Bryant ◽  
Hervé Philippe
Keyword(s):  
Amino Acid ◽  
Amino Acid Sequence ◽  
Tertiary Structure ◽  
Sequence Evolution

scholarly journals Frequent Detection of Escape from Cytotoxic T-Lymphocyte Recognition in Perinatal Human Immunodeficiency Virus (HIV) Type 1 Transmission: the Ariel Project for the Prevention of Transmission of HIV from Mother to Infant

1999 ◽  
Vol 73 (5) ◽  
pp. 3975-3985 ◽  
Author(s):  
Cara C. Wilson ◽  
R. Clark Brown ◽  
Bette T. Korber ◽  
Barbara M. Wilkes ◽  
Debbie J. Ruhl ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Amino Acid ◽  
Amino Acid Sequence ◽  
Sequence Variation ◽  
Amino Acid Sequence Variation ◽  
Immunodeficiency Virus ◽  
Immunologic Factors ◽  
Hiv Type 1 ◽  
Hiv 1

ABSTRACT Host immunologic factors, including human immunodeficiency virus (HIV)-specific cytotoxic T lymphocytes (CTL), are thought to contribute to the control of HIV type 1 (HIV-1) replication and thus delay disease progression in infected individuals. Host immunologic factors are also likely to influence perinatal transmission of HIV-1 from infected mother to infant. In this study, the potential role of CTL in modulating HIV-1 transmission from mother to infant was examined in 11 HIV-1-infected mothers, 3 of whom transmitted virus to their offspring. Frequencies of HIV-1-specific human leukocyte antigen class I-restricted CTL responses and viral epitope amino acid sequence variation were determined in the mothers and their infected infants. Maternal HIV-1-specific CTL clones were derived from each of the HIV-1-infected pregnant women. Amino acid substitutions within the targeted CTL epitopes were more frequently identified in transmitting mothers than in nontransmitting mothers, and immune escape from CTL recognition was detected in all three transmitting mothers but in only one of eight nontransmitting mothers. The majority of viral sequences obtained from the HIV-1-infected infant blood samples were susceptible to maternal CTL. These findings demonstrate that epitope amino acid sequence variation and escape from CTL recognition occur more frequently in mothers that transmit HIV-1 to their infants than in those who do not. However, the transmitted virus can be a CTL susceptible form, suggesting inadequate in vivo immune control.

scholarly journals Sequence variation of the HVR1 region of Hepatitis C virus in response to interferon-α and ribavirin treatment

2011 ◽  
Vol 5 (05) ◽  
pp. 370-376 ◽  
Author(s):  
Ahmed Ali Al-Qahtani ◽  
Salvatore Rubino ◽  
Mohammed N. Al-Ahdal
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Amino Acid ◽  
Amino Acid Sequence ◽  
Sequence Variation ◽  
Amino Acid Sequences ◽  
Interferon Α ◽  
Genotype 4 ◽  
Treatment Protocols ◽  
Sequence Variations

Introduction: Hepatitis C virus (HCV), which is a major cause of liver diseases worldwide, undergoes genetic variation during the course of infection. The aim of this study was to examine sequence variations within the HVR1 region of HCV genotype 4 in infected Saudi patients treated with a combination therapy of interferon-α and ribavirin. Methodology: cDNA of the HVR1 region of HVC-4 from one responder and one non-responder patients was generated, cloned and sequenced. Ten clones were randomly selected and analyzed for changes in nucleotide and amino acid sequences before the start of treatment, and subsequently three and six months after the start of the therapy course. Results: Based on nucleotide and amino acid sequence variations, the HVR1 region is highly sequence variable. In both the responder and the non-responder patients, amino acid sequence variations were observed and a clear distinction between patients was evident. The amino acid changes after the treatment course were different in the responder compared to the non-responder subject. Five amino acids (residues 364 to 367, 381 and 409) were unique in the non-responder patient. Conclusion: Considerable amino acid variations were observed in the HVR1 region in both responder and non-responder patients. These findings could have implications for the development of an HCV vaccine as well as treatment protocols for HCV infections.

scholarly journals The Wzz (Cld) Protein in Escherichia coli: Amino Acid Sequence Variation Determines O-Antigen Chain Length Specificity

1998 ◽  
Vol 180 (10) ◽  
pp. 2670-2675 ◽  
Author(s):  
Agustin V. Franco ◽  
Dan Liu ◽  
Peter R. Reeves
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Amino Acid Sequence ◽  
Chain Length ◽  
Sequence Variation ◽  
Length Distribution ◽  
Chain Length Distribution ◽  
E Coli ◽  
O Antigen ◽  
Amino Acid Sequence Variation

ABSTRACT The O antigen is a polymer with a repeated unit. The chain length in most Escherichia coli strains has a modal value of 10 to 18 O units, but other strains have higher or lower modal values.wzz (cld/rol) mutants have a random chain length distribution, showing that the modal distribution is determined by the Wzz protein. Cloned wzz genes from E. coli strains with short (7 to 16), intermediate (10 to 18), and long (16 to 25) modal chain lengths were transferred to a model system, and their effects on O111 antigen were studied. The O111 chain length closely resembled that of the parent strains. We present data based on the construction of chimeric wzz genes and site-directed mutagenesis of the wzz gene to show that the modal value of O-antigen chain length of E. coli O1, O2, O7, and O157 strains can be changed by specific amino acid substitutions in wzz. It is concluded that the O-antigen chain length heterogeneity in E. coli strains is the result of amino acid sequence variation of the Wzz protein.

Structure and evolution of mammalian ribosomal proteins

1995 ◽  
Vol 73 (11-12) ◽  
pp. 933-947 ◽  
Author(s):  
Ira G. Wool ◽  
Yuen-Ling Chan ◽  
Anton Glück
Keyword(s):  
Amino Acid ◽  
Amino Acid Sequence ◽  
Nuclear Localization ◽  
Ribosomal Proteins ◽  
Sequence Evolution ◽  
Sequence Motifs ◽  
Nuclear Localization Signals ◽  
Zinc Finger Domains ◽  
Relationship Of ◽  
The Relationship

Mammalian (rat) ribosomes have 80 proteins; the sequence of amino acids in 75 have been determined. What has been learned of the structure of the rat ribosomal proteins is reviewed with particular attention to their evolution and to amino acid sequence motifs. The latter include: clusters of basic or acidic residues; sequence repeats or shared sequences; zinc finger domains; bZIP elements; and nuclear localization signals. The occurrence and the possible significance of phosphorylated residues and of ubiquitin extensions is noted. The characteristics of the mRNAs that encode the proteins are summarized. The relationship of the rat ribosomal proteins to the proteins in ribosomes from humans, yeast, archaebacteria, and Escherichia coli is collated.Key words: ribosomes, ribosomal proteins, amino acid sequence, evolution.

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