A distinct interphase microtubule state marks host cell permissiveness to Chlamydia pneumoniae entry

Entry of intracellular pathogenic bacteria is widely considered an actin-driven process, potentially overlooking contributions of the microtubule cytoskeleton. Interphase microtubules exist in distinct states, but whether this heterogeneity influences bacterial entry is unknown. Here, using the obligate intracellular bacterium Chlamydia pneumoniae, we show that microtubules not only contribute to bacterial entry but that their pre-existing state influences host-cell permissiveness. Cells enriched in acetylated microtubules are preferentially infected, whereas detyrosinated microtubules show no such association. Taxol enhances entry, whereas selective elevation of microtubule acetylation with Tubacin does not, indicating that acetylation itself is insufficient and pointing instead to a permissive state associated with stabilized, long-lived microtubules. We next show that this relationship is reciprocal: infection induces a dose-dependent increase in microtubule acetylation that requires bacterial viability and is not reproduced by uptake of Yersinia pseudotuberculosis Invasin-coated beads, indicating that internalization alone is insufficient to trigger this response. Finally, to examine how early chlamydial proteins can alter microtubule behaviour, we assessed the effect of the secreted TarP-family actin–microtubule regulator CPn0572 on microtubule stability. In the Schizosaccharomyces pombe in vivo test system, CPn0572 promotes microtubule persistence and can act together with another chlamydial microtubule modulator to generate a combined microtubule phenotype. Together, these findings identify the pre-existing microtubule state as a determinant of Chlamydia pneumoniae entry, show that infection subsequently remodels the microtubule cytoskeleton, and demonstrate that an early chlamydial protein can directly alter microtubule behaviour.