Environmental Chlamydiae Alter the Growth Speed and Motility of Host Acanthamoebae

Abstract

Symbiosis between living beings is an important driver of evolutionary novelty and ecological diversity; however, understanding the mechanisms underlying obligate mutualism remains a significant challenge. Regarding this, we have previously isolated two different Acanthamoeba strains harboring endosymbiotic bacteria, Protochlamydia (R18 symbiotic amoebae: R18WT) or Neochlamydia (S13 symbiotic amoebae; S13WT). In this study, we treated the symbiotic amoebae R18WT and S13WT with doxycycline (DOX) and rifampicin (RFP), respectively, to establish the aposymbiotic amoebae R18DOX and S13RFP, respectively. Subsequently, we compared the growth speed, motility, phagocytosis, pinocytosis, and morphology of the symbiotic and aposymbiotic amoebae. The growth speed of R18DOX was decreased, although that of S13RFP was increased. A marked change in motility was observed only for R18DOX amoebae. There was no difference in phagocytic and pinocytic activities between the symbiotic and aposymbiotic amoebae. Meanwhile, we observed a significant change in the phalloidin staining pattern and morphological changes in R18DOX (but not S13RFP) aposymbiotic amoebae, indicating a change in actin accumulation upon removal of the Protochlamydia. Infection of C3 (a reference strain) or S13RFP amoebae with Protochlamydia had a harmful effect on the host amoebae, but R18DOX amoebae re-infected with Protochlamydia showed recovery in both growth speed and motility. Taken together, we conclude that endosymbiont environmental chlamydiae alter the growth speed and/or motility of their host Acanthamoeba, possibly implying an close mutual relationship between amoebae and environmental chlamydiae.

High‐temperature adapted primitive Protochlamydia found in Acanthamoeba isolated from a hot spring can grow in immortalized human epithelial HEp‐2 cells

“…Several studies have revealed host–bacterium symbiotic relationships with clear benefits to the hosts, such as aphids, tsetse flies, ants and worms, where the bacterial endosymbionts provide essential amino acids (Douglas, ), vitamin B complexes (Snyder et al ., ) and fatty acids (Zientz et al ., ). We also have reported that a primitive chlamydia ( Protochlamydia R18) intimately regulates host amoebal motility through actin reconstitution, possibly assisting amoebae to obtain nutrients from surrounded bacteria (Okude et al ., ). Such a relationship may explain why HS‐T3 amoebae tolerate the endosymbiotic Protochlamydia .…”

Icm/Dot-dependent inhibition of phagocyte migration byLegionellais antagonized by a translocated Ran GTPase activator

“…Finally, obligate intracellular bacteria of the genus Chlamydia also modulate cell migration. Whereas C. trachomatis was found to inhibit the non-directed migration of HeLa cells (Heymann et al, 2013), C. pneumoniae promotes cell adhesion and migration of vascular smooth muscle cells (Zhang et al, 2012), and endosymbiotic environmental Chlamydia control the motility of host Acanthamoeba (Okude et al, 2012).…”

Amoebal Endosymbiont Neochlamydia Genome Sequence Illuminates the Bacterial Role in the Defense of the Host Amoebae against Legionella pneumophila

“…The prevalence of amoebae with endosymbionts, as defined by 4′,6-diamidino-2-phenylindole staining, was always approximately 100% [6]. Acanthamoeba castellanii C3 (ATCC 50739) was purchased from the American Type Culture Collection (ATCC) and used as a reference strain.…”