Shoichi Tachiyama
Research & Publications
Biography
Research Summary
Many gram-negative bacteria develop large protein complexes on their bacterial membranes that contribute to pathogenesis. The type III secretion system (T3SS), also called injectisome, and flagella are large protein complexes on bacterial membranes. Shigella develops and uses T3SS to directly translocate bacterial proteins into eukaryotic cells to change host cell functions, thereby reaping bacterial benefits by impacting immune system responses and bacterial motility within hosts. Although T3SS is essential to Shigella pathogenesis, the structural details and functions of each protein are not clearly understood. Previously, cryo-ET revealed an architecture on the cytoplasmic side of Shigella T3SS on minicells resulting from abnormal cell divisions. This location, called the cytoplasmic sorting platform, is an important protein complex to select and translocate bacterial proteins into host cells. Our laboratory has focused on structural details of the sorting platform to understand how bacterial proteins are injected into eukaryotic cells. To understand molecular functions of proteins in the sorting platform, our laboratory has collaborated with Dr. William Picking, University of Kansas. In our additional investigations of the flagella system, we also collaborate with Dr. Timothy Hoover, University of Georgia. We focus on architectures of flagella in Helicobacter pylori, a pathogen that uses flagella to localize in the human stomach to cause gastritis and peptic ulcer. This work aims to elucidate how H. pylori regulates flagella assembly. Our laboratory uses cryo-ET to observe the architecture of flagella structures on both bacterial membranes, termed the motor, which contribute to bacterial motility.
Coauthors
Research Interests
Flagella; Molecular Structure; Cryoelectron Microscopy; Host-Pathogen Interactions
Selected Publications
- Bacterial flagella hijack type IV pili proteins to control motilityLiu X, Tachiyama S, Zhou X, Mathias R, Bonny S, Khan M, Xin Y, Roujeinikova A, Liu J, Ottemann K. Bacterial flagella hijack type IV pili proteins to control motility. Proceedings Of The National Academy Of Sciences Of The United States Of America 2024, 121: e2317452121. PMID: 38236729, PMCID: PMC10823254, DOI: 10.1073/pnas.2317452121.
- FlgV forms a flagellar motor ring that is required for optimal motility of Helicobacter pyloriBotting J, Tachiyama S, Gibson K, Liu J, Starai V, Hoover T. FlgV forms a flagellar motor ring that is required for optimal motility of Helicobacter pylori. PLOS ONE 2023, 18: e0287514. PMID: 37976320, PMCID: PMC10655999, DOI: 10.1371/journal.pone.0287514.
- Bacteria require phase separation for fitness in the mammalian gutKrypotou E, Townsend G, Gao X, Tachiyama S, Liu J, Pokorzynski N, Goodman A, Groisman E. Bacteria require phase separation for fitness in the mammalian gut. Science 2023, 379: 1149-1156. PMID: 36927025, PMCID: PMC10148683, DOI: 10.1126/science.abn7229.
- Composition and Biophysical Properties of the Sorting Platform Pods in the Shigella Type III Secretion SystemTachiyama S, Skaar R, Chang Y, Carroll BL, Muthuramalingam M, Whittier SK, Barta ML, Picking WL, Liu J, Picking WD. Composition and Biophysical Properties of the Sorting Platform Pods in the Shigella Type III Secretion System. Frontiers In Cellular And Infection Microbiology 2021, 11: 682635. PMID: 34150677, PMCID: PMC8211105, DOI: 10.3389/fcimb.2021.682635.
- The Structures of SctK and SctD from Pseudomonas aeruginosa Reveal the Interface of the Type III Secretion System Basal Body and Sorting PlatformMuthuramalingam M, Whittier SK, Lovell S, Battaile KP, Tachiyama S, Johnson DK, Picking WL, Picking WD. The Structures of SctK and SctD from Pseudomonas aeruginosa Reveal the Interface of the Type III Secretion System Basal Body and Sorting Platform. Journal Of Molecular Biology 2020, 432: 166693. PMID: 33122003, PMCID: PMC10550303, DOI: 10.1016/j.jmb.2020.10.027.
- The cytoplasmic domain of MxiG interacts with MxiK and directs assembly of the sorting platform in the Shigella type III secretion systemTachiyama S, Chang Y, Muthuramalingam M, Hu B, Barta ML, Picking WL, Liu J, Picking WD. The cytoplasmic domain of MxiG interacts with MxiK and directs assembly of the sorting platform in the Shigella type III secretion system. Journal Of Biological Chemistry 2019, 294: 19184-19196. PMID: 31699894, PMCID: PMC6916477, DOI: 10.1074/jbc.ra119.009125.
- Using disruptive insertional mutagenesis to identify the in situ structure‐function landscape of the Shigella translocator protein IpaBBarta ML, Tachiyama S, Muthuramalingam M, Arizmendi O, Villanueva CE, Ramyar KX, Geisbrecht BV, Lovell S, Battaile KP, Picking WL, Picking WD. Using disruptive insertional mutagenesis to identify the in situ structure‐function landscape of the Shigella translocator protein IpaB. Protein Science 2018, 27: 1392-1406. PMID: 29672980, PMCID: PMC6153406, DOI: 10.1002/pro.3428.