Tamara O’Connor
The outcome of most parasitic relationships is decided by an elaborate series of events involving hundreds of proteins. Understanding this interaction requires the analysis of the molecular mechanisms operating in both organisms and the causal relationships acting at the interface between them. The O’Connor lab studies the molecular basis of infectious disease with a particular emphasis on the network of molecular interactions acting at the host-pathogen interface. Using Legionella pathogenesis as a model system, we are defining the various mechanisms by which an intracellular bacterial pathogen can establish infection, how they exploit host cell machinery to accomplish this, and how individual proteins and their component pathways coordinately contribute to disease. In parallel, we investigate how virulence strategies arise in environmental reservoirs as a consequence of bacterial interactions with protozoa and the role of these natural hosts in driving bacterial transmission and disease in humans.
Current Lab Members
| Name | Role | |
| Saumya Bandyopadhyay | Postdoctoral fellow | sbandyo5@jhmi.edu |
| Katya Romanov | Graduate student (PhD) | kromano4@jhmi.edu |
| Arwa Talat | Graduate student (MSc) | atalat1@jh.edu |
| Nicholas Humberto Perez | Research Technologist | nperez10@jh.edu |
| Emily Stroud | Research Technician | estroud2@jhu.edu |
| Josh Khorsandi | Undergraduate Student | jkhorsa1@jhu.edu |
| Sarah Zhao | Undergraduate Student | szhao56@jhu.edu |
| Aceyln McGowan | Undergraduate Student | amcgowa3@jh.edu |
| Tair Alibekov | Undergraduate Student | talibek1@jh.edu |
| Ananya Srinivasan | Undergraduate Student | asrini18@jh.edu |
Publications
Hossain, MJ, Romanov KA, Jian J, Swaby LC, Bandyopadhyay S, Guan I, Thomas SM, Olive AJ, O’Connor TJ (2024) Bacterial pathogens hijack host cell peroxisomes for replication vacuole membrane expansion and integrity. Science Adv. 11:eadr8005.
Vijayrajratnam S, Patkowski J, Khorsandi J, Beatty W, Kannaiah S, Hasanovic A, O’Connor TJ, Costa T, Vogel JP. (2025) Optimized Legionella expression strain for affinity purification of His-tagged membrane proteins eliminates major multimeric contaminant. Microbiology Spectrum. 13:e0322224.
Romanov K, O’Connor TJ (2024) Legionella pneumophila, a Rosetta stone to understanding bacterial pathogenesis. Special Series on The History of Microbial Model Systems. J Bacteriol. 5: e0032424.
Ghosh S, Bandyopadhyay S, Smith DM, Adak S, Semenkovich CF, Nagy L, Wolfgang MJ, O’Connor TJ. (2024) Legionella usurps host cell lipids for vacuole expansion and bacterial growth. PLoS Pathogens. 20:e1011996.
Shin CJ, O’Connor TJ. (2024) Novel induction of broad-spectrum antibiotics by the human pathogen Legionella.
mSphere. e0012024.
Choi J, Smith DM, Lee YJ, Cai D, Hossain MJ, O’Connor TJ, Deme P, Haughey NJ, Scafidi S, Riddle RC, Wolfgang M. (2024) Etomoxir: A Promiscuous Fatty Acid Mimetic Chemoproteomic Probe. iScience. 27:110642.
Boamah D, Gilmore MC, Bourget S, Ghosh A, Hossain MJ, Vogel JP, Cava F, O’Connor TJ. (2023) Peptidoglycan deacetylation controls Type IV secretion and the intracellular survival of the bacterial pathogen Legionella pneumophila. Proc Natl Acad Sci USA. 120:e2119658120.
Allen C, Banks D, Shuster M, Vogel S, O’Connor TJ, Briken V. (2023) Legionella pneumophila inhibits type I interferon signaling to avoid cell-intrinsic host cell defense. Infect Immun. 16:e0036523.
Hossain MJ, O’Connor TJ. (2023) An efficient and cost-effective method for disrupting genes in RAW264.7 macrophages using CRISPR-Cas9. PLoS One. 19(3):e0299513.
Shin CJ, O’Connor TJ. (2022) Complete genome sequence of Bacillus safensis Strain AHB2, isolated from African raw honey from Kajo Keji, South Sudan. Microbial Res Ann. 11:e0051522.
Shin CJ, O’Connor TJ. (2022) Complete genome sequence of an African raw honey bacterial isolate, Bacillus safensis Strain AHB11. Microbial Res Ann. 11:e0051622.
Park JM, Ghosh S, O’Connor TJ. (2020) Combinatorial selection in environmental hosts drives the evolution of a human pathogen. Nat Microbiol. 5:599.
Boamah DK, Zhou G, Ensminger AW, O’Connor TJ (2017) From many hosts, one accidental pathogen: the diverse protozoan hosts of Legionella. Front Cell Infect Microbiol. 7:477.
Ghosh S and O’Connor TJ. (2017) Beyond paralogs: the multiple layers of redundancy in bacterial pathogenesis. Front Cell Infect Microbiol. 7:467.
O’Connor TJ, Zheng H, VanRheenen SM, Ghosh S, Cianciotto NP, Isberg RR (2016) Iron triggers early egress by the intracellular bacterial pathogen Legionella pneumophila. Infect Immun. 84:2185-2197.
O’Connor TJ, Isberg RR (2014) iMAD: a genetic screening strategy to dissect complex interaction between a pathogen and its host. Nature Protocols. 9:1916-1930.
O’Connor TJ, Boyd D, Dorer M, Isberg RR (2012) Aggravating genetic interactions allow a solution to redundancy in a bacterial pathogen. Science 338:1440-1444.
O’Connor TJ, Adepoju Y, Boyd D, Isberg RR (2011) Minimization of the Legionella pneumophila genome reveals chromosomal regions involved in host range expansion.Proc Natl Acad Sci 108:14733-14740.
Isberg RR, O’Connor TJ, Heidtman M (2009) The Legionella pneumophila replication vacuole: making a cosy niche inside host cells. Nature Reviews Microbiology 7:13-24.
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