The twin-arginine translocation pathway in a-proteobacteria is functionally preserved irrespective of genomic and regulatory divergence

The twin-arginine translocation (Tat) pathway exports fully folded proteins out of the cytoplasm of Gram-negative and Gram-positive bacteria. Although much progress has been made in unraveling the molecular mechanism and biochemical characterization of the Tat system, little is known concerning its functionality and biological role to confer adaptive skills, symbiosis or pathogenesis in the alpha-proteobacteria class. A comparative genomic analysis in the ?-proteobacteria class confirmed the presence of tatA, tatB, and tatC genes in almost all genomes, but significant variations in gene synteny and rearrangements were found in the order Rickettsiales with respect to the typically described operon organization. Transcription of tat genes was confirmed for Anaplasma marginale str. St. Maries and Brucella abortus 2308, two alpha-proteobacteria with full and partial intracellular lifestyles, respectively. The tat genes of A. marginale are scattered throughout the genome, in contrast to the more generalized operon organization. Particularly, tatA showed an approximately 20-fold increase in mRNA levels relative to tatB and tatC. We showed Tat functionality in B. abortus 2308 for the first time, and confirmed conservation of functionality in A. marginale. We present the first experimental description of the Tat system in the Anaplasmataceae and Brucellaceae families. In particular, in A. marginale Tat functionality is conserved despite operon splitting as a consequence of genome rearrangements. Further studies will be required to understand how the proper stoichiometry of the Tat protein complex and its biological role are achieved. In addition, the predicted substrates might be the evidence of role of the Tat translocation system in the transition process from a free-living to a parasitic lifestyle in these alpha-proteobacteria.

Bibliographic Details

Main Authors:	Nuñez, P. A., Soria, M., Farber, M. D.
Format:	article biblioteca
Language:	eng
Subjects:	BACTERIAL PROTEIN, MESSENGER RNA, TAT A PROTEIN, TAT B PROTEIN, TAT C PROTEIN, UNCLASSIFIED DRUG, BACTERIAL RNA, CARRIER PROTEIN, ESCHERICHIA COLI PROTEIN, TWIN ARGININE TRANSLOCASE COMPLEX, E COLI, ANAPLASMA MARGINALE, BACTERIAL GENE, BACTERIAL GENOME, BACTERIAL SECRETION SYSTEM, BRUCELLA ABORTUS, CELL PHENOTYPE, GENE REARRANGEMENT, GENETIC ORGANIZATION, GENETIC TRANSCRIPTION, GENOME ANALYSIS, HETEROLOGOUS EXPRESSION, NONHUMAN, NUCLEOTIDE SEQUENCE, OPERON, PHENOTYPE, PHYLOGENY, PROTEIN EXPRESSION, PROTEIN FUNCTION, SYNTENY, TATA GENE, TATB GENE, TATC GENE, TWIN ARGININE TRANSLOCATION PATHWAY, ALPHAPROTEOBACTERIA, AMINO ACID SEQUENCE, COMPARATIVE STUDY, ESCHERICHIA COLI, GENETIC COMPLEMENTATION, GENETIC VARIABILITY, GENETICS, METABOLISM, MOLECULAR GENETICS, MULTIGENE FAMILY, PROTEIN TRANSPORT, SEQUENCE HOMOLOGY, SPECIES DIFFERENCE, ANAPLASMA MARGINALE STR. ST. MARIES, ANAPLASMATACEAE, BRUCELLA MELITENSIS BIOVAR ABORTUS, BRUCELLACEAE, NEGIBACTERIA, POSIBACTERIA, RICKETTSIALES, GENETIC COMPLEMENTATION TEST, GENETIC VARIATION, GENOME, BACTERIAL, MEMBRANE TRANSPORT PROTEINS, MOLECULAR SEQUENCE DATA, RNA, BACTERIAL, RNA, MESSENGER, SEQUENCE HOMOLOGY, AMINO ACID, SPECIES SPECIFICITY,
Online Access:	http://ri.agro.uba.ar/greenstone3/library/collection/arti/document/2012Nunez
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