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name:Novick, richard

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148


Reconstitution of the S. aureus agr quorum sensing pathway reveals a direct role for the integral membrane protease MroQ in pheromone biosynthesis

Zhao, Aishan; Bodine, Steven P; Xie, Qian; Wang, Boyuan; Ram, Geeta; Novick, Richard P; Muir, Tom W
In Staphylococcus aureus, virulence is under the control of a quorum sensing (QS) circuit encoded in the accessory gene regulator (agr) genomic locus. Key to this pathogenic behavior is the production and signaling activity of a secreted pheromone, the autoinducing peptide (AIP), generated following the ribosomal synthesis and posttranslational modification of a precursor polypeptide, AgrD, through two discrete cleavage steps. The integral membrane protease AgrB is known to catalyze the first processing event, generating the AIP biosynthetic intermediate, AgrD (1-32) thiolactone. However, the identity of the second protease in this biosynthetic pathway, which removes an N-terminal leader sequence, has remained ambiguous. Here, we show that membrane protease regulator of agr QS (MroQ), an integral membrane protease recently implicated in the agr response, is directly involved in AIP production. Genetic complementation and biochemical experiments reveal that MroQ proteolytic activity is required for AIP biosynthesis in agr specificity group I and group II, but not group III. Notably, as part of this effort, the biosynthesis and AIP-sensing arms of the QS circuit were reconstituted together in vitro. Our experiments also reveal the molecular features guiding MroQ cleavage activity, a critical factor in defining agr specificity group identity. Collectively, our study adds to the molecular understanding of the agr response and Staphylococcus aureus virulence.
PMID: 35939668
ISSN: 1091-6490
CID: 5286582

Dynamics of Antibacterial Drone Establishment in Staphylococcus aureus: Unexpected Effects of Antibiotic Resistance Genes

Dhasmana, Neha; Ram, Geeta; McAllister, Kathleen N; Chupalova, Yulia; Lopez, Peter; Ross, Hope F; Novick, Richard P
The antibacterial drone (ABD) system is based on repurposing the phage-inducible staphylococcal pathogenicity islands (SaPIs) for use as antibacterial agents that are indifferent to antibiotic resistance. The ABDs were constructed by inserting tetM for tetracycline resistance (Tcr) selection, replacing the SaPI virulence genes with bactericidal or bacteriostatic genes such as CRISPR/cas9/agrA, whose expression kills by double-strand cleavage of agrA, or CRISPR/dcas9/agrP2P3
PMCID:8593670
PMID: 34781740
ISSN: 2150-7511
CID: 5103832

Antibacterial particles and predatory bacteria as alternatives to antibacterial chemicals in the era of antibiotic resistance

Novick, Richard P
This review is focused on the subset of antibacterial agents whose action involves one-on-one targeting of infecting bacteria. These agents target individual bacteria and their efficacy is based on particle numbers in contrast to chemical agents such as antibiotics, whose efficacy is based on minimal inhibitory concentrations. Four extant members of this class are predatory bacteria, functional (plaque-forming) phages, and engineered particulate systems, phagemids (plasmids that contain a phage packaging signal) and antibacterial drones (ABDs) that package chromosomal island DNA carrying antibacterial genes. We differentiate the natural predators, phages and predatory bacteria, from the engineered delivery vehicles, phagemids and ABDs, because the latter are much more versatile and can largely bypass the historical warfare that informs the predator-prey interactions.
PMID: 34688038
ISSN: 1879-0364
CID: 5068232

A regulatory cascade controls Staphylococcus aureus pathogenicity island activation

Haag, Andreas F; Podkowik, Magdalena; Ibarra-Chávez, Rodrigo; Gallego Del Sol, Francisca; Ram, Geeta; Chen, John; Marina, Alberto; Novick, Richard P; Penadés, José R
Staphylococcal pathogenicity islands (SaPIs) are a family of closely related mobile chromosomal islands that encode and disseminate the superantigen toxins, toxic shock syndrome toxin 1 and superantigen enterotoxin B (SEB). They are regulated by master repressors, which are counteracted by helper phage-encoded proteins, thereby inducing their excision, replication, packaging and intercell transfer. SaPIs are major components of the staphylococcal mobilome, occupying five chromosomal att sites, with many strains harbouring two or more. As regulatory interactions between co-resident SaPIs could have profound effects on the spread of superantigen pathobiology, we initiated the current study to search for such interactions. Using classical genetics, we found that, with one exception, their regulatory systems do not cross-react. The exception was SaPI3, which was originally considered defective because it could not be mobilized by any known helper phage. We show here that SaPI3 has an atypical regulatory module and is induced not by a phage but by many other SaPIs, including SaPI2, SaPIbov1 and SaPIn1, each encoding a conserved protein, Sis, which counteracts the SaPI3 repressor, generating an intracellular regulatory cascade: the co-resident SaPI, when conventionally induced by a helper phage, expresses its sis gene which, in turn, induces SaPI3, enabling it to spread. Using bioinformatics analysis, we have identified more than 30 closely related coancestral SEB-encoding SaPI3 relatives occupying the same att site and controlled by a conserved regulatory module, immA-immR-str'. This module is functionally analogous but unrelated to the typical SaPI regulatory module, stl-str. As SaPIs are phage satellites, SaPI3 and its relatives are SaPI satellites.
PMID: 34518655
ISSN: 2058-5276
CID: 5012292

Discovery of quorum quenchers targeting the membrane-embedded sensor domain of the Staphylococcus aureus receptor histidine kinase, AgrC

Xie, Qian; Wiedmann, Mareike M; Zhao, Aishan; Pagan, Ivelisse R; Novick, Richard P; Suga, Hiroaki; Muir, Tom W
We combined mRNA display technology with lipid-nanodisc based selections and identified high-affinity ligands targeting the integral membrane sensor domain of the histidine kinase AgrC as potent inhibitors of Staphylococcus aureus quorum sensing-modulated virulence. Our study highlights the potential of this integrated approach for identifying functional modulators of integral membrane proteins.
PMCID:7530097
PMID: 32820778
ISSN: 1364-548x
CID: 4637802

Targeted killing of virulent Vibrio cholerae

Novick, Richard
PMID: 31209355
ISSN: 2157-846x
CID: 3939032

Pathogenicity Islands and Their Role in Staphylococcal Biology

Novick, Richard P
Pathogenicity islands are members of a vast collection of genomic islands that encode important virulence, antibiotic resistance and other accessory functions and have a critical role in bacterial gene transfer. Staphylococcus aureus is host to a large family of such islands, known as SaPIs, which encode super antigen and other virulence determinants, are mobilized by helper phages and transferred at extremely high frequencies. They benefit their host cells by interfering with phage predation and enhancing horizontal gene transfer. This chapter describes their life cycle, the bases of their phage interference mechanisms, their transfer system and their conversion to antibacterial agents for treatment ofstaphylococcal infections.
PMID: 31172913
ISSN: 2165-0497
CID: 3923572

Identification of a Molecular Latch that Regulates Staphylococcal Virulence

Xie, Qian; Zhao, Aishan; Jeffrey, Philip D; Kim, Minyoung Kevin; Bassler, Bonnie L; Stone, Howard A; Novick, Richard P; Muir, Tom W
Virulence induction in the Staphylococcus aureus is under the control of a quorum sensing (QS) circuit encoded by the accessory gene regulator (agr) locus. Allelic variation within agr produces four QS specificity groups, each producing a unique secreted autoinducer peptide (AIP) and receptor histidine kinase (RHK), AgrC. Cognate AIP-AgrC interactions activate virulence through a two-component signaling cascade, whereas non-cognate pairs are generally inhibitory. Here we pinpoint a key hydrogen-bonding interaction within AgrC that acts as a switch to convert helical motions propagating from the receptor sensor domain into changes in inter-domain association within the kinase module. AgrC mutants lacking this interaction are constitutively active in vitro and in vivo, the latter leading to a pronounced attenuation of S. aureus biofilm formation. Thus, our work sheds light on the regulation of this biomedically important RHK.
PMID: 30773482
ISSN: 2451-9448
CID: 3687722

Pathogenecity Islands and Their Role in Staphylococcal Biology

Novick, Richard P.
ISI:000482713600013
ISSN: 2165-0497
CID: 4071702

Conversion of staphylococcal pathogenicity islands to CRISPR-carrying antibacterial agents that cure infections in mice

Ram, Geeta; Ross, Hope F; Novick, Richard P; Rodriguez-Pagan, Ivelisse; Jiang, Dunrong
Staphylococcus aureus and other staphylococci continue to cause life-threatening infections in both hospital and community settings. They have become increasingly resistant to antibiotics, especially β-lactams and aminoglycosides, and their infections are now, in many cases, untreatable. Here we present a non-antibiotic, non-phage method of treating staphylococcal infections by engineering of the highly mobile staphylococcal pathogenicity islands (SaPIs). We replaced the SaPIs' toxin genes with antibacterial cargos to generate antibacterial drones (ABDs) that target the infecting bacteria in the animal host, express their cargo, kill or disarm the bacteria and thus abrogate the infection. Here we have constructed ABDs with either a CRISPR-Cas9 bactericidal or a CRISPR-dCas9 virulence-blocking module. We show that both ABDs block the development of a murine subcutaneous S. aureus abscess and that the bactericidal module rescues mice given a lethal dose of S. aureus intraperitoneally.
PMID: 30247487
ISSN: 1546-1696
CID: 3315912