The Twin-Arginine Translocation Pathway in α-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 α-proteobacteria class. A comparative genomic analysis in the α-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 α-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 α-proteobacteria

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Not AvailableIntroduction: Nosocomial infections are a notorious subset of infectious diseases, varying between 10% and 20% prevalence worldwide. The infections are concomitant with various treatment complications, multiple-drug resistance, and a high degree of virulence. Klebsiella pneumoniae is a gram-negative bacteria of nosocomial importance. Objectives: Our current study is gauged to reason and understand why, despite treatment with cutting-edge medicines and technology, the K. pneumoniae remains elusive. Methods: Using various in silico tools, the KPHS_00890 hypothetical protein of K. pneumoniae subsp. pneumoniae HS11286 was identified and annotated. Results: A thorough investigation revealed that KPHS_00890 hypothetical protein is a bifunctional 5′-nucleotidase, an enzyme catalyzing the degradation of nucleotides to nucleosides. Conclusions: Scrutiny and review of the 5′-nucleotidase function across various species ascertained its pertinent role in immune evasion, by suppressing inflammatory responses. Thus, having identified the KPHS_00890 hypothetical protein of K. pneumoniae subsp. pneumoniae HS11286 as a 5′-nucleotidase, we propose that it may be involved in an immune evasion strategy during infection pathogenesis.Not Availabl