Watanabe T, Yamazaki S, Maita C, Matushita M, Matsuo J, Okubo T, Yamaguchi H. Lateral Gene Transfer Between Protozoa-Related Giant Viruses of Family
Mimiviridae and Chlamydiae.
Evol Bioinform Online 2018;
14:1176934318788337. [PMID:
30038484 PMCID:
PMC6050620 DOI:
10.1177/1176934318788337]
[Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Accepted: 06/21/2018] [Indexed: 11/23/2022] Open
Abstract
Obligate intracellular chlamydiae diverged into pathogenic and environmental
chlamydiae 0.7-1.4 billion years ago. While pathogenic chlamydiae have adapted
to a wide range of vertebrates, environmental chlamydiae inhabit unicellular
amoebae, the free-living Acanthamoeba. However, how and why
this divergence occurred remains unclear. Meanwhile, giant viruses consisting of
protozoa-related and protozoa-unrelated viruses have been discovered, with the
former group being suggested to have more influenced environmental chlamydiae
during their evolution while cohabiting host amoebae. Against this background,
we attempted to visualize genes of giant viruses in chlamydial genomes by
bioinformatic analysis mainly with comparative genome and phylogenic analysis,
seeking genes present in chlamydiae that are specifically shared with
protozoa-related giant viruses. As a result, in contrast to protozoa-unrelated
giant viruses, the genes of protozoa-related giant viruses were significantly
shared in both the chlamydia genomes depending on the giant virus type. In
particular, the prevalence of Mimiviridae genes among the
protozoa-related giant virus genes in chlamydial genomes was significantly high.
Meanwhile, the prevalence of protozoa-related giant virus genes in pathogenic
chlamydia genomes was consistently higher than those of environmental
chlamydiae; the actual number of sequences similar to giant virus was also
significantly predominant compared with those in the environmental chlamydial
genomes. Among them, the most prevalent of giant virus was in the case of
chlamydiae with Megavirus chiliensis; total of 1338 genes of
the chlamydiae were found to be shared with the virus (444 genes specific to
environmental chlamydiae, 892 genes shared between both chlamydiae, only two
genes in the pathogenic chlamydiae). Phylogenic analysis with most prevalent
sets (Megavirus chiliensis and Protochlamydia
EI2 or Chlamydia trachomatis L2 434Bu) showed the presence of
orthologs between these with several clustered. In addition, Pearson’s single
regression analysis revealed that almost the prevalence of the genes from the
giant viruses in chlamydial genomes was negatively and specifically correlated
with the number of chlamydial open reading frames (ORFs). Thus, these results
indicated the trace of lateral gene transfer between protozoa-related giant
viruses of family Mimiviridae and chlamydiae. This is the first
demonstration of a putative linkage between chlamydiae and the giant viruses,
providing us with a hint to understand chlamydial evolution.
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