Moving simply: Naegleria crawls and feeds using an ancient Arp2/3-dependent mechanism

Arp2/3-nucleated actin filaments drive crawling motility and phagocytosis in animal cells and slime molds. In this issue, Velle and Fritz-Laylin (2020. J. Cell Biol.https://doi.org/10.1083/jcb.202007158) now show that Naegleria gruberi, belonging to a lineage that diverged from opisthokonts around a billion years ago, uses similar mechanisms to crawl and phagocytose bacteria.

Insight into motility-dependent pathogenicity of the zoonotic spirochete Leptospira

Bacterial motility is crucial for many pathogenic species in the process of invasion and/or dissemination. The spirochete bacteria Leptospira spp. cause symptoms, such as hemorrhage, jaundice, and nephritis, in diverse mammals including humans. Although loss-of-motility attenuate the spirochete, the mechanism of the motility-dependent pathogenicity is unknown. Here, focusing on that Leptospira spp. swim in liquid and crawl on solid surfaces, we investigated the spirochetal dynamics on the host tissues by infecting cultured kidney cells from various species with pathogenic and nonpathogenic leptospires. We found that, in the case of the pathogenic leptospires, a larger fraction of bacteria attached to the host cells and persistently traveled long distances using the crawling mechanism. Our results associate the kinetics and kinematic features of the spirochetal pathogens with their virulence.One Sentence SummaryAdhesivity and crawling motility over host tissue surfaces are closely related to the pathogenicity of a zoonotic spirochete.