Oral Presentation 25th International Pathogenic Neisseria Conference 2026

How Neisseria gonorrhoeae contends with both zinc limitation and zinc excess during infection (140638)

Amy L Forehand 1 , Ian K Liyayi 1 , Mallory R Lane 1 , Aloke K Bera 2 , Indu Bhatia 3 , Nourin Ferdausi 2 , Kinga Malezyna 1 , Yasiru R Perera 3 , Nicholas Noinaj 2 , Ahmad Jomaa 1 , Walter J Chazin 3 , Julie Stoudenmire 4 , Cynthia N Cornelissen 4 , Alison K Criss 1
  1. University of Virginia, Charlottesville, VA, United States
  2. Purdue University, West Lafayette, IN, USA
  3. Vanderbilt University, Nashville, TN, USA
  4. Georgia State University, Atlanta, GA, USA

Neisseria gonorrhoeae (Gc) must contend with both toxic, millimolar concentrations of zinc found in seminal plasma and immune cell phagosomes, and zinc limitation at mucosal surfaces, where zinc is sequestered by metal-binding nutritional immunity proteins. We are investigating how Gc responds to the range of zinc concentrations encountered in the human host to define how metal availability impacts bacterial physiology and pathogenesis. Gc responds to zinc limitation by derepressing the Zur regulon, which increases production of TonB-dependent transporters that extract zinc from human calprotectin and psoriasin, and the ZnuABC inner membrane zinc import system. We previously defined the transcriptome of zinc-restricted strain FA1090 Gc (Ray et al, PMID 35156850). In this regulon, we discovered Zcp (encoded by ngo1049), a periplasmic zinc-binding protein that helps Gc grow in zinc-limited conditions by maintaining metalation of extracytoplasmic clients. We also found that zinc-limited Gc induces the rpmE2-rpmJ2 operon (ngo0930-ngo0931), encoding two non-zinc-binding ribosomal proteins. These proteins are paralogs of canonical RpmE and RpmJ, respectively, which contain zinc-binding CXXC motifs. In other bacteria, non-zinc-binding alternative ribosomal proteins replace zinc-binding canonical ribosomal proteins, which are degraded to make zinc bioavailable. In contrast, ribosomes from zinc-limited Gc contain both RpmE and RpmE2. Surprisingly, Gc deleted for rpmE2-rpmJ2 have a growth advantage in zinc-depleted medium. Moreover, Gc engineered to only make RpmE2 have a severe, zinc-independent growth defect. From these results, we hypothesize that zinc-starved Gc produces alternative ribosomal proteins to slow growth until zinc availability improves. Regarding zinc excess, we found Gc is sensitive to millimolar concentrations of zinc in chemically defined medium. Putative bacterial metal transporters modulate sensitivity of Gc to high zinc concentrations, with our results suggesting that intracellular concentrations of other metals are concomitantly reduced. However, Gc grows in seminal simulant medium, which contains 2.5 mM zinc, suggesting Gc can contend with excess zinc in physiologically relevant environments. These results highlight the complexity of how Gc contends with the varied zinc concentrations experienced in the human host, which could be targeted for new antigonococcal strategies.