A Distinct Interphase Microtubule State Marks Host Cell Permissiveness to Chlamydia pneumoniae Entry

Abstract

Entry of intracellular pathogenic bacteria is widely considered an actin-driven process, potentially overlooking contributions of the microtubule cytoskeleton. Here, we identify a host microtubule state as a determinant of early infection efficiency by Chlamydia pneumoniae. Human cells enriched in acetylated microtubules are preferentially infected, whereas detyrosinated microtubules show no such association. Pharmacological stabilization of microtubules via Taxol enhances infection, while selective elevation of acetylation with Tubacin does not, indicating that microtubule stability rather than acetylation alone is critical. Thus, a pre-existing interphase microtubule architecture supports C. pneumoniae entry. Consistently, mitotic cells, characterized by a reorganized microtubule architecture, remain permissive but show severely reduced infection efficiency. In addition, infection induces a dose-dependent increase in microtubule acetylation that requires bacterial viability and is not observed during uptake of Yersinia pseudotuberculosis effector protein Invasin-coated beads, indicating that entry/internalization alone is insufficient to trigger this response. To probe how early chlamydial secreted effectors might engage the microtubule cytoskeleton, we focused on the conserved TarP family member CPn0572, an actin and microtubule regulator, which increases microtubule acetylation when ectopically expressed in human cells. Controlled expression of microtubule-localized CPn0572 in the yeast Schizosaccharomyces pombe leads to altered microtubule dynamic and mechanical behaviour, promoting force-bearing microtubules. Together, these findings show that distinct interphase microtubules define a permissive cellular state for bacterial entry and suggest that early chlamydial effector activities might promote a specific microtubule persistence phenotype.