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- nkorotkova@uky.edu
- 859-323-5493
- BBSRB B279
The major focus of my research program is to understand the organization and functioning of cell wall envelope in streptococci and other medically important Gram-positive pathogens with the purpose of development of highly targeted therapeutics to control infections caused by these bacteria. Gram-positive bacteria are surrounded by a thick cell wall consisting of peptidoglycan with covalently attached glycopolymers. Group A Streptococci (GAS), or Streptococcus pyogenes, is a human pathogen responsible for substantial worldwide morbidity and mortality. GAS peptidoglycan is decorated with the Lancefield group A carbohydrate (GAC) which consists of a polyrhamnose backbone with N-acetylglucosamine (GlcNAc) side-chains. Understanding the molecular structure and function of GAC is of paramount importance for developing new approaches to combat GAS because GAC plays an essential role in GAS viability and virulence. Moreover, GAC has been previously targeted for vaccine development and used in clinical diagnostics. A 12-gene locus (gacABCDEFGHIJKL) responsible for GAC biosynthesis was identified and characterized by mutagenesis. Our recent work revealed the molecular mechanism of GlcNAc side-chain attachment to polyrhamnose. Using molecular genetics, analytical chemistry and mass spectrometry analysis, we defined the functions of gacI, gacJ and gacL in this biosynthetic pathway.
Schematic diagram of GAC biosynthesis.
GAC is anchored to peptidoglycan presumably via phosphodiester bond. GAC biosynthesis is initiated on the inner leaflet of the plasma membrane where GacO produces GlcNAc-P-P-Und which serves as a membrane-anchored acceptor for polyrhamnose synthesis catalyzed by the GacB, GacC, GacF and GacG rhamnosyltransferases. Following polymerization polyrhamnose is transferred to the outer leaflet of the membrane presumably by the GacD/ GacE ABC transporter. Also in the inner leaflet of the membrane, GacI aided by GacJ produces GlcNAc-P-Und which then diffuses across the plasma membrane to the outer leaflet aided by GacK. Subsequently, GacL transfers GlcNAc to polyrhamnose using GlcNAc-P-Und as glycosyl donor. Lastly, protein members of LytR-CpsA-Psr (LCP) phosphotransferase family presumably attach GAC to peptidoglycan. Several details of this biosynthetic scheme are still speculative and further research will be required to definitively confirm this hypothetical pathway, but the overall organization is consistent with other isoprenol-mediated polysaccharide biosynthesis pathways.
Korotkova N., Hoff J.S., Becker D.M., Quinn J.K., Icenogle L.M., Moseley S.L. SpyA is a
membrane-bound ADP-ribosyltransferase of Streptococcus pyogenes which modifies a
streptococcal peptide, SpyB. (2012) Mol. Microbiol. 83(5):936-952. PubMed PMID: 22288436. doi: 10.1111/j.1365-2958.2012.07979.x.
Tchesnokova V., Aprikian P., Kisiela D., Gowey S., Korotkova N., Thomas W.,
Sokurenko E. Type 1 fimbrial adhesin FimH elicits an immune response that
enhances cell adhesion of Escherichia coli. (2011) Infect. Immun. 79(10):3895-3904. PubMed PMID: 21768279. doi: 10.1128/IAI.05169-11.
Liévin-Le Moal V., Beau I., Rougeaux C., Kansau I., Fabrega S., Brice C., Korotkova
N., Moseley S.L., Servin A.L. Apical expression of human full-length hCEACAM1-4L
protein renders the Madin Darby Canine Kidney cells responsive to
lipopolysaccharide leading to TLR4-dependent Erk1/2 and p38 MAPK signalling. (2011) Cell Microbiol. 13(5):764-785. PubMed PMID: 21352462. doi: 10.1111/j.1462-5822.2011.01575.x.
Korotkova N., Yarova-Yarovaya Y., Tchesnokova V., Yazvenko N., Carl M.A., Stapleton
A.E., Moseley S.L. Escherichia coli DraE adhesin-associated bacterial
internalization by epithelial cells is promoted independently by
decay-accelerating factor and carcinoembryonic antigen-related cell adhesion
molecule binding and does not require the DraD invasin. (2008) Infect. Immun. 76(9):3869-3880. PubMed PMID: 18559426. doi: 10.1128/IAI.00427-08.
Korotkova N., Yang Y., Le Trong I., Cota E., Demeler B., Marchant J., Thomas W.E.,
Stenkamp R.E., Moseley S.L., Matthews S. Binding of Dr adhesins of Escherichia coli
to carcinoembryonic antigen triggers receptor dissociation. (2008) Mol. Microbiol. 67(2):420-434. PubMed PMID: 18086185. doi: 10.1111/j.1365-2958.2007.06054.x. ProteinDataBank 2VER, 2QSQ, 2QST.
Korotkova N., Chattopadhyay S., Tabata T.A., Beskhlebnaya V., Vigdorovich V., Kaiser
B.K., Strong R.K., Dykhuizen D.E., Sokurenko E.V., Moseley SL. Selection for functional
diversity drives accumulation of point mutations in Dr adhesins of Escherichia
coli. (2007) Mol. Microbiol. 64(1):180-194. PubMed PMID: 17376081. doi: 10.1111/j.1365-2958.2007.05648.x.
Korotkova N., Cota E., Lebedin Y., Monpouet S., Guignot J., Servin A.L., Matthews S.,
Moseley S.L. A subfamily of Dr adhesins of Escherichia coli bind independently to
decay-accelerating factor and the N-domain of carcinoembryonic antigen. (2006) J. Biol.
Chem. 281(39):29120-29130. PubMed PMID: 16882658. doi: 10.1074/jbc.M605681200.
Korotkova N., Le Trong I., Samudrala R., Korotkov K., Van Loy C.P., Bui A.L., Moseley
S.L., Stenkamp R.E. Crystal structure and mutational analysis of the DaaE adhesin of
Escherichia coli. (2006) J. Biol. Chem. 281(31):22367-22377. PubMed PMID: 16751628. doi: 10.1074/jbc.M604646200. ProteinDataBank 2BCM.
Kalyuzhnaya M.G., Korotkova N., Crowther G., Marx C.J., Lidstrom M.E., Chistoserdova
L. Analysis of gene islands involved in methanopterin-linked C1 transfer
reactions reveals new functions and provides evolutionary insights. (2005) J. Bacteriol.
187(13):4607-4614. PubMed PMID: 15968072. doi: 10.1128/JB.187.13.4607-4614.2005.
Korotkova N., Lidstrom M.E., Chistoserdova L. Identification of genes involved
in the glyoxylate regeneration cycle in Methylobacterium extorquens AM1,
including two new genes, meaC and meaD. (2005) J. Bacteriol. 187(4):1523-1526.
PubMed PMID: 15687219. doi: 10.1128/JB.187.4.1523-1526.2005.
Korotkova N., Lidstrom M.E. MeaB is a component of the methylmalonyl-CoA mutase
complex required for protection of the enzyme from inactivation. (2004) J. Biol. Chem.
279(14):13652-13658. PubMed PMID: 14734568. doi: 10.1074/jbc.M312852200.
Korotkova N., Chistoserdova L., Lidstrom M.E. Poly-beta-hydroxybutyrate
biosynthesis in the facultative methylotroph methylobacterium extorquens AM1:
identification and mutation of gap11, gap20, and phaR. (2002) J. Bacteriol. 184(22):6174-6181. PubMed PMID: 12399487. doi: 10.1128/JB.184.22.6174-6181.2002.
Korotkova N., Chistoserdova L., Kuksa V., Lidstrom M.E. Glyoxylate regeneration
pathway in the methylotroph Methylobacterium extorquens AM1. (2002) J. Bacteriol. 184(6):1750-1758. PubMed PMID: 11872727. doi: 10.1128/JB.184.6.1750-1758.2002.
Korotkova N., Lidstrom M.E. Connection between poly-beta-hydroxybutyrate
biosynthesis and growth on C(1) and C(2) compounds in the methylotroph
Methylobacterium extorquens AM1. (2001) J. Bacteriol. 183(3):1038-1046. PubMed PMID: 11208803. doi: 10.1128/JB.183.3.1038-1046.2001.
- "SpyB, a Small Heme-Binding Protein, Affects the Composition of the Cell Wall in <i>Streptococcus pyogenes</i>." Frontiers in cellular and infection microbiology 6, (2016): 126. [PubMed Link] |
- "Type 1 fimbrial adhesin FimH elicits an immune response that enhances cell adhesion of Escherichia coli." Infection and immunity 79, 10 (2011): 3895-904. [PubMed Link] | [ Full text ]
- "Escherichia coli DraE adhesin-associated bacterial internalization by epithelial cells is promoted independently by decay-accelerating factor and carcinoembryonic antigen-related cell adhesion molecule binding and does not require the DraD invasin." Infection and immunity 76, 9 (2008): 3869-80. [PubMed Link] | [ Full text ]
- "Binding of Dr adhesins of Escherichia coli to carcinoembryonic antigen triggers receptor dissociation." Molecular microbiology 67, 2 (2008): 420-34. [PubMed Link] | [ Full text ]
- "Selection for functional diversity drives accumulation of point mutations in Dr adhesins of Escherichia coli." Molecular microbiology 64, 1 (2007): 180-94. [PubMed Link] | [ Full text ]
- "A subfamily of Dr adhesins of Escherichia coli bind independently to decay-accelerating factor and the N-domain of carcinoembryonic antigen." The Journal of biological chemistry 281, 39 (2006): 29120-30. [PubMed Link] | [ Full text ]
- "Crystal structure and mutational analysis of the DaaE adhesin of Escherichia coli." The Journal of biological chemistry 281, 31 (2006): 22367-77. [PubMed Link] | [ Full text ]
- "Analysis of gene islands involved in methanopterin-linked C1 transfer reactions reveals new functions and provides evolutionary insights." Journal of bacteriology 187, 13 (2005): 4607-14. [PubMed Link] | [ Full text ]
- "Identification of genes involved in the glyoxylate regeneration cycle in Methylobacterium extorquens AM1, including two new genes, meaC and meaD." Journal of bacteriology 187, 4 (2005): 1523-6. [PubMed Link] | [ Full text ]
- "MeaB is a component of the methylmalonyl-CoA mutase complex required for protection of the enzyme from inactivation." The Journal of biological chemistry 279, 14 (2004): 13652-8. [PubMed Link] | [ Full text ]
- "Reconstruction of C(3) and C(4) metabolism in Methylobacterium extorquens AM1 using transposon mutagenesis." Microbiology (Reading, England) 149, Pt 3 (2003): 601-9. [PubMed Link] | [ Full text ]
- "Poly-beta-hydroxybutyrate biosynthesis in the facultative methylotroph methylobacterium extorquens AM1: identification and mutation of gap11, gap20, and phaR." Journal of bacteriology 184, 22 (2002): 6174-81. [PubMed Link] | [ Full text ]
- "Glyoxylate regeneration pathway in the methylotroph Methylobacterium extorquens AM1." Journal of bacteriology 184, 6 (2002): 1750-8. [PubMed Link] | [ Full text ]
- "Connection between poly-beta-hydroxybutyrate biosynthesis and growth on C(1) and C(2) compounds in the methylotroph Methylobacterium extorquens AM1." Journal of bacteriology 183, 3 (2001): 1038-46. [PubMed Link] | [ Full text ]