Quick Soniya R, Bains Jason S, Gerdt Catherine, Walker Bryan, Goldstone Eleanor B, Jakuszeit Theresa, Baggaley Andrew W, Croze Ottavio A, Gerdt Joseph P
Department of Chemistry, Indiana University, Bloomington, Indiana, United States of America.
School of Mathematics, Statistics and Physics, Newcastle University, Newcastle upon Tyne, United Kingdom.
PLoS Pathog. 2025 Sep 3;21(9):e1013440. doi: 10.1371/journal.ppat.1013440.
Regulated motility is vital for many cells-both for unicellular microbes and for cells within multicellular bodies. Different conditions require different rates and directions of movement. For the microbial predator Capsaspora owczarzaki, its motility is likely essential for predation. This organism has been shown to prey on diverse organisms, including the schistosome parasites that co-reside with it in Biomphalaria glabrata snails. Capsaspora is also one of the closest living unicellular relatives of animals. This phylogenic placement makes Capsaspora's motility an attractive target for understanding the evolution of motility in animal cells. Until now, little was known of how Capsaspora regulates its rate and direction of motility. Here we found that it exhibits chemokinesis (increased movement in response to chemical factors) in response to proteins released from prey cells. Chemokinesis also occurs in response to pure proteins-including bovine serum albumin. We found that this chemokinesis behavior is dependent on Capsaspora cell density, which suggests that the regulated motility is a cooperative behavior (possibly to improve cooperative feeding). We developed a mathematical model of Capsaspora motility and found that chemokinesis can benefit Capsaspora predation. In this model, Capsaspora moved in random trajectories. Chemotaxis (directional motility along a chemical gradient toward prey) is likely to synergize with this chemokinesis to further improve predation. Finally, we quantitatively analyzed Capsaspora's previously reported chemotaxis behavior. These findings lay a foundation for characterizing the mechanisms of regulated motility in a predator of a human pathogen and a model for the ancestor of animals.
对于许多细胞而言，无论是单细胞微生物还是多细胞生物体内的细胞，受调控的运动能力都至关重要。不同的条件需要不同的运动速率和方向。对于微生物捕食者奥氏尖孢虫（Capsaspora owczarzaki）来说，其运动能力可能对捕食至关重要。这种生物已被证明会捕食多种生物，包括与它共同生活在光滑双脐螺（Biomphalaria glabrata）体内的血吸虫寄生虫。奥氏尖孢虫也是现存与动物亲缘关系最近的单细胞生物之一。这种系统发育位置使得奥氏尖孢虫的运动能力成为理解动物细胞运动进化的一个有吸引力的研究对象。到目前为止，人们对奥氏尖孢虫如何调节其运动速率和方向知之甚少。在这里，我们发现它会对猎物细胞释放的蛋白质产生趋化性运动（对化学因子做出反应而增加运动）。对纯蛋白质（包括牛血清白蛋白）也会产生趋化性运动。我们发现这种趋化性运动行为依赖于奥氏尖孢虫的细胞密度，这表明受调控的运动是一种合作行为（可能是为了改善合作进食）。我们建立了一个奥氏尖孢虫运动的数学模型，发现趋化性运动对奥氏尖孢虫的捕食有益。在这个模型中，奥氏尖孢虫沿随机轨迹移动。趋化作用（沿着化学梯度向猎物进行定向运动）可能会与这种趋化性运动协同作用，以进一步提高捕食效率。最后，我们对奥氏尖孢虫先前报道的趋化作用行为进行了定量分析。这些发现为阐明人类病原体捕食者中受调控运动的机制以及动物祖先模型奠定了基础。
