Research Description

Membrane Protein Structural Biology

Proteins and small molecules are translocated across lipid bilayers by integral membrane proteins that span the bilayer and facilitate translocation. My lab centers around determining the atomic resolution structure of membrane proteins and complexes that function to transport materials across lipid bilayers. The primary focus of research in the lab is nutrient uptake mechanisms within Gram negative bacterial species. In addition to the structural and biochemical characterization of these ion transport system components, research in my lab also examines the membrane protein complexes that facilitate the proper insertion and assembly of these membrane protein transport components including surface anchored lipoproteins.

Slam-dependent surface lipoprotein translocation

Lipoproteins decorate the surface of many obligate host restricted Gram-negative bacterial pathogens, playing essential roles in immune evasion and nutrient acquisition. In Neisseria spp., the causative agents of gonorrhea and meningococcal meningitis, surface lipoproteins (SLPs) such as factor H-binding protein (fHbp) and transferrin binding protein B (TbpB) are required for virulence and are primary targets for broad-spectrum vaccine development since they elicit bactericidal antibodies.  The surface lipoprotein assembly modulator (Slam) is required for the proper assembly of SLPs on the surface of Gram negative bacteria and is required for virulence. The mechanism of Slam and the translocation of SLPs is fundamental for the survival of these host restricted bacteria.

Iron acquisition through the bacterial transferrin receptor

In the vertebrate host, the level of free extracellular iron is well below that required to support the growth of bacterial pathogens, largely owing to the iron-sequestering effects of iron-binding glycoproteins transferrin and lactoferrin. Successful bacterial pathogens have developed high-affinity iron uptake systems capable of acquiring iron from transferrin and lactoferrin. Members of the Neisseriacea and Pasteurellaceae family including Neisseria meningitidis and Haemophilus influenza possess receptors consisting of the surface exposed lipoprotein TbpB and the integral outer membrane protein TbpA that bind transferrin and are involved in the retrieval and transport of iron across the outer membrane. Within the periplasm, the ferric binding protein, FbpA, binds iron and escorts it to the inner membrane ABC transporter where it is transported into the cytoplasm (Figure 1).

Nutrient transport across the Gram-negative cell Envelope

Phosphate plays an essential role in nearly all metabolic, catabolic, and signaling events within virtually all living organisms. As such, the trafficking of phosphate anions is an immensely important function, yet the specific mechanism utilized to transport inorganic phosphate molecules across a lipid bilayer remains unclear. The Gram negative bacterial cell utilizes a double membrane system and employs a plethora of channels that can be constitutive or specifically expressed in its outer membrane (OM) in response to various environmental conditions. Most bacteria, including Pseudomonas react to environmental conditions of low phosphate by turning on a gene regulon leading to the expression of a number of phosphate trafficking proteins (Figure 2). This regulation is mediated by regulatory proteins anchored in the inner membrane (PhoR), that sense phosphate levels through an as yet uncharacterized interaction with the inner membrane transport complex.

Publications

View all publications on PubMed

Reverse vaccinology-based identification of a novel surface lipoprotein that is an effective vaccine antigen against bovine infections caused by Pasteurella multocida.
Islam EA, Fegan JE, Tefera TA, Curran DM, Waeckerlin RC, Ng D, Ahn SK, Lai CHR, Nguyen QH, Shah M, Tesfaw L, Adamu K, Medhin WW, Legesse A, Deresse G, Getachew B, Rawlyk N, Evans B, Potter A, Schryvers AB, Gray-Owen SD, Moraes TF.
PLoS Pathog. 2023 Mar 24;19(3):e1011249.   Read

Reconstitution of surface lipoprotein translocation through the slam translocon.
Huynh MS, Hooda Y, Li YR, Jagielnicki M, Lai CC, Moraes TF.
Elife. 2022 Apr 27;11:e72822.   Read

Structural and Mechanistic Insight into CRISPR-Cas9 Inhibition by Anti-CRISPR Protein AcrIIC4Hpa.
Hwang S, Pan C, Garcia B, Davidson AR, Moraes TF, Maxwell KL.
J Mol Biol. 2022 Mar 15;434(5):167420.   Read

A Slam-dependent hemophore contributes to heme acquisition in the bacterial pathogen Acinetobacter baumannii.
Bateman TJ, Shah M, Ho TP, Shin HE, Pan C, Harris G, Fegan JE, Islam EA, Ahn SK, Hooda Y, Gray-Owen SD, Chen W, Moraes TF.
Nature Communications. 2021 Nov 1;12(1):6270.   Read

Actinobacillus utilizes a binding protein-dependent ABC transporter to acquire the active form of vitamin B6.
Pan C, Zimmer A, Shah M, Huynh MS, Chieh-Lin Lai C, Sit B, Hooda Y, Curran DM, Moraes TF.
Journal of Biological Chemistry. 2021 Aug 3:101046. doi: 10.1016/j.jbc.2021.101046. PMID: 34358566  Read

A phage-encoded anti-activator inhibits quorum sensing in Pseudomonas aeruginosa.
Shah M, Taylor VL, Bona D, Tsao Y, Stanley SY, Pimentel-Elardo SM, McCallum M, Bondy-Denomy J, Howell PL, Nodwell JR, Davidson AR, Moraes TF, Maxwell KL.
Molecular Cell. 2021 Jan 4:S1097-2765(20)30903-5.  Read

Lactoferrin receptors in Gram-negative bacteria: an evolutionary perspective.
Ostan NKH, Moraes TF, Schryvers AB.
Biochem Cell Biol. 2021 Jan 19:1-7. doi: 10.1139/bcb-2020-0079.   Read

The surface lipoproteins of gram-negative bacteria: Protectors and foragers in harsh environments.
Cole GB, Bateman TJ, Moraes TF.
J Biol Chem. 2021 Jan-Jun;296:100147.   Read

Transferrin binding protein B and Transferrin binding protein A 2 expand the transferrin recognition range of Histophilus somni.
AK Pogoutse, TF Moraes
Journal of Bacteriology 2020 Jun 25;202(14):e00177-20.   Read

Inhibition of CRISPR-Cas9 ribonucleoprotein complex assembly by anti-CRISPR AcrIIC2.
Thavalingam A, Cheng Z, Garcia B, Huang X, Shah M, Sun W, Wang M, Harrington L, Hwang S, Hidalgo-Reyes Y, Sontheimer EJ, Doudna J, Davidson AR, Moraes TF, Wang Y, Maxwell KL
Nature Communications. 2019 Jun 26;10(1):2806.   Read

Utility of Hybrid Transferrin Binding Protein Antigens for Protection Against Pathogenic Neisseria Species.
Fegan JE, Calmettes C, Islam EA, Ahn SK, Chaudhuri S, Yu RH, Gray-Owen SD, Moraes TF, Schryvers AB.
Frontiers Immunology 2019 Feb 19;10:247.   Read

Slam is an outer membrane protein that is required for the surface display of lipidated virulence factors in Neisseria
Y. Hooda, C.C. Lai, A. Judd, C. Buckwalter, H.E. Shin, S.D. Gray-Owen, and T.F. Moraes.
Nature Microbiology 1 (2016).  Read

Structural biology of solute carrier (SLC) membrane transport proteins.
Bai X,Moraes TF, Reithmeier RAF.
Mol Membr Biol. 2018 Apr 13:1-32.   Read

Translocation of lipoproteins to the surface of gram negative bacteria.
Hooda Y, Moraes TF.
Curr Opin Struct Biol. 2018 Mar 23;51:73-79.   Read

Disabling a Type I-E CRISPR-Cas Nuclease with a Bacteriophage-Encoded Anti-CRISPR Protein.
Pawluk A, Shah M, Mejdani M, Calmettes C, Moraes TF, Davidson AR, Maxwell KL.
MBio. 2017 Dec 12;8(6). pii: e01751-17.  Read

Identification of a Large Family of Slam-Dependent Surface Lipoproteins in Gram-Negative Bacteria.
Hooda Y, Lai CCL, Moraes TF.
Front Cell Infect Microbiol. 2017 May 31;7:207.   Read

Neisserial surface lipoproteins: structure, function and biogenesis.
Hooda Y, Shin HE, Bateman TJ, Moraes TF.
Pathog Dis. 2017 Mar 1;75(2). doi: 10.1093/femspd/ftx010.   Read

Iron acquisition through the bacterial transferrin receptor.
Pogoutse AK, Moraes TF.
Crit Rev Biochem Mol Biol. 2017 Jun;52(3):314-326.   Read

Lactoferrin binding protein B - a bi-functional bacterial receptor protein.
Ostan NK, Yu RH, Ng D, Lai CC, Pogoutse AK, Sarpe V, Hepburn M, Sheff J, Raval S, Schriemer DC, Moraes TF, Schryvers AB.
PLoS Pathog. 2017 Mar 3;13(3):e1006244.   Read

A method for measuring binding constants using unpurified in vivo biotinylated ligands.
Anastassia K. Pogoutse, Christine C. Lai, Nick Ostan, Rong-hua Yu, Anthony B. Schryvers, Trevor F. Moraes.
Anal Biochem. 2016 Feb 17.  Read

The molecular mechanism of Zinc acquisition by the Neisserial outer-membrane receptor ZnuD.
Charles Calmettes, Christopher Ing, Carolyn M. Buckwalter, Majida El Bakkouri, Christine Chieh-Lin Lai, Pogoutse A, Scott D Gray-Owen, Régis Pomès and Trevor F. Moraes.
Nature Communications 2015 Aug 18;6:7996.  Read

Active Transport of Phosphorylated Carbohydrates Promotes Intestinal Colonization and Transmission of a Bacterial Pathogen.
Brandon Sit, Shauna M. Crowley, Kirandeep Bhullar, Christine Chieh-Lin Lai, Calvin Tang, Yogesh Hooda, Charles Calmettes, Husain Khambati, Caixia Ma, John H. Brumell, Anthony B. Schryvers, Bruce A. Vallance, and Trevor F. Moraes.
PLoS Pathog. 2015 Aug 21;11(8):e1005107. doi: 10.1371  Read

Nonbinding site-directed mutants of transferrin binding protein B enhances their immunogenicity and protective capabilities.
Frandoloso R, Martínez-Martínez S, Calmettes C, Fegan J, Costa E, Curran D, Yu R, Gutiérrez-Martín CB, Rodríguez Ferri EF, Moraes TF, Schryvers AB.
Infect Immun. 2014 Dec 29  Read

A substrate access tunnel in the cytosolic domain is not an essential feature of the solute carrier 4 (SLC4) family of bicarbonate transporters.
Shnitsar V, Li J, Li X, Calmettes C, Basu A, Casey JR, Moraes TF, Reithmeier RA.
J Biol Chem. 2013 Nov 22;288(47):33848-60  Read

The structural basis of transferrin sequestration by transferrin-binding protein B.
Calmettes C, Alcantara J., Yu RH, Schryvers AB, Moraes T.F.
Nat Struct Mol Biol. 2012 Feb 19;19(3):358-60.  Read

Bacterial receptors for host transferrin and lactoferrin: molecular mechanisms and role in host-microbe interactions.
Morgenthau A, Pogoutse A, Adamiak P, Moraes TF, Schryvers AB.
Future Microbiol. 2013 Dec;8(12):1575-85.  Read

Membrane transport metabolons.
Moraes TF, Reithmeier RA.
Biochim Biophys Acta. 2012 Nov;1818(11):2687-706.  Read

Structural variations within the transferrin binding site on transferrin-binding protein B, TbpB.
Calmettes C, Yu RH, Silva LP, Curran D, Schriemer DC, Schryvers AB, Moraes TF.
J Biol Chem. 2011 Apr 8;286(14):12683-92  Read

Insights into the bacterial transferrin receptor: the structure of transferrin-binding protein B from Actinobacillus pleuropneumoniae.
Moraes TF, Yu RH, Strynadka NC, Schryvers AB
Mol Cell. 2009 Aug 28;35(4):523-33.  Read

An arginine ladder in OprP mediates phosphate-specific transfer across the outer membrane.
Moraes TF, Bains M, Hancock RE, Strynadka NC.
Nat Struct Mol Biol. 2007 Jan;14(1):85-7.  Read