Papers by Sarbani Bhattacharya
... Thank you for sticking with me during my need. I would like to thank Dr. Shreemanta K. Parida... more ... Thank you for sticking with me during my need. I would like to thank Dr. Shreemanta K. Parida, Dr. Mayuri Pandu and Subhamay Bhattacharya for patiently bearing my occasional bouts of frustration and their encouragement and support. ...
Journal of Biological Chemistry, Aug 1, 2014
Background: High affinity human plasminogen (hPg) binding to Group A Streptococcus (GAS) is media... more Background: High affinity human plasminogen (hPg) binding to Group A Streptococcus (GAS) is mediated by the coiledcoil M-like protein, PAM. Results: Amino acid residues in the a1a2 domain of PAM direct high affinity PAM/hPg binding regardless of oligomerization status of PAM. Conclusion: The a1a2 domain defines its hPg binding site, regardless of PAM dimerization. Significance: The virulence of GAS is altered by mutations in PAM(a1a2). A emm53 subclass of Group A Streptococcus pyogenes (GAS) interacts tightly with human plasma plasminogen (hPg) and plasmin (hPm) via the kringle 2 (K2 hPg) domain of hPg/hPm and the N-terminal a1a2 regions of a GAS coiled-coil M-like protein (PAM). Previous studies have shown that a monomeric PAM fragment, VEK30 (residues 97-125 ؉ Tyr), interacted specifically with isolated K2 hPg. However, the binding strength of VEK30 (K D ؍ 56 nM) was ϳ60-fold weaker than that of full-length dimeric PAM (K D ؍ 1 nM). To assess whether this attenuated binding was due to the inability of VEK30 to dimerize, we defined the minimal length of PAM required to dimerize using a series of peptides with additional PAM residues placed at the NH 2 and COOH termini of VEK30. VEK64 (PAM residues 83-145 ؉ Tyr) was found to be the smallest peptide that adopted an ␣-helical dimer, and was bound to K2 hPg with nearly the same affinity as PAM (K D ؍ 1-2 nM). However, addition of two PAM residues (Arg 126-His 127) to the COOH terminus of VEK30 (VEK32) maintained a monomeric peptidic structure, but exhibited similar K2 hPg binding affinity as full-length dimeric PAM. We identified five residues in a1a2 (Arg 113 , His 114 , Glu 116 , Arg 126 , His 127), mutation of which reduced PAM binding affinity for K2 hPg by ϳ1000-fold. Replacement of these critical residues by Ala in the GAS genome resulted in reduced virulence, similar to the effects of inactivating the PAM gene entirely. We conclude that rather than dimerization of PAM, the five key residues in the binding domain of PAM are essential to mediate the high affinity interaction with hPg, leading to increased GAS virulence. More than 200 M-protein-based serotypes of Group A Streptococcus pyogenes (GAS) 2 exist that cause Ͼ700 million cases of human pharyngeal and dermal infections worldwide each year. These infections range from non-invasive pharyngitis and impetigo, to severe and treatment-resistant forms of infectious diseases, e.g. necrotizing fasciitis and streptococcal toxic shock syndrome, as well as postinfectious nonpyogenic diseases, e.g. rheumatic fever and glomuleronephritis. Because of the existence of these latter highly virulent strains of GAS, which lead to high morbidity and oftentimes death, virulence factors of GAS have been sought for vaccine development as a global health issue. All GAS strains contain a form of a surface-resident M-protein, which is housed in a virulence operon of GAS under control of the multiple gene activator, mga (1). A subset of these M-proteins present in skin-tropic highly virulent strains of GAS bind with high affinity to host human plasma plasminogen (hPg), and this interaction is a critical determinant of the virulence of these strains (2). All GAS strains secrete a hPg activator, streptokinase, which, through a series of steps, converts GAS-bound hPg to the serine protease, plasmin (hPm) (3). The hPm remains bound to GAS, thus providing GAS to a proteolytic surface. This feature enables GAS to degrade encapsulating fibrin and, directly or indirectly, extracellular matrix proteins, thereby encouraging higher infectivity and systemic dissemination of the bacteria (4). The noncatalytic chain of hPm and corresponding regions of hPg contain five ϳ80 residue triple disulfide-linked kringle (K) domains (5). The main functions of kringle motifs are to mediate the binding of hPg to activation effectors and bind to relevant receptors and other proteins. Chief among the ligands for kringles is Lys and Lys analogues, with K1 hPg , K4 hPg , and K5 hPg showing highest affinity for Lys. K2 hPg possesses the lowest Lys binding strength for Lys binding kringles (6-9) and K3 hPg does not possess a binding site for Lys (10). The physiological role for
Journal of Biomedicine and Biotechnology, 2012
In order for invasive pathogens to migrate beyond the site of infection, host physiological barri... more In order for invasive pathogens to migrate beyond the site of infection, host physiological barriers such as the extracellular matrix, the basement membrane, and encapsulating fibrin network must be degraded. To circumvent these impediments, proteolytic enzymes facilitate the dissemination of the microorganism. Recruitment of host proteases to the bacterial surface represents a particularly effective mechanism for enhancing invasiveness. Plasmin is a broad spectrum serine protease that degrades fibrin, extracellular matrices, and connective tissue. A large number of pathogens express plasminogen receptors which immobilize plasmin(ogen) on the bacterial surface. Surface-bound plasminogen is then activated by plasminogen activators to plasmin through limited proteolysis thus triggering the development of a proteolytic surface on the bacteria and eventually assisting the spread of bacteria. The host hemostatic system plays an important role in systemic infection. The interplay between hemostatic processes such as coagulation and fibrinolysis and the inflammatory response constitutes essential components of host defense and bacterial invasion. The goal of this paper is to highlight mechanisms whereby pathogenic bacteria, by engaging surface receptors, utilize and exploit the host plasminogen and fibrinolytic system for the successful dissemination within the host.
Copyright © 2012 Sarbani Bhattacharya et al. This is an open access article distributed under the... more Copyright © 2012 Sarbani Bhattacharya et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. In order for invasive pathogens to migrate beyond the site of infection, host physiological barriers such as the extracellular matrix, the basement membrane, and encapsulating fibrin network must be degraded. To circumvent these impediments, proteolytic enzymes facilitate the dissemination of the microorganism. Recruitment of host proteases to the bacterial surface represents a particularly effective mechanism for enhancing invasiveness. Plasmin is a broad spectrum serine protease that degrades fibrin, extracellular matrices, and connective tissue. A large number of pathogens express plasminogen receptors which immobilize plasmin(ogen) on the bacterial surface. Surface-bound plasminogen is then activated by plasminogen activato...
In Head and Neck Squamous Cell Carcinomas (HNSCC), positive margins after surgical resection domi... more In Head and Neck Squamous Cell Carcinomas (HNSCC), positive margins after surgical resection dominate the clinical outcome of patients. Between 15-30 percent of all HNSCC surgeries result in a positive margin (>5 mm) that requires postoperative chemo-radiation, radiotherapy, and/or revision surgeries. To minimize local recurrence, margin assessment is typically performed through surgical pathology departments; however, this technique often takes more than 24 hours to process and only a small fraction of the total surgical margin is evaluated. A second, intraoperative approach used by surgeons to minimize local recurrence is frozen section analysis (FSA), which is time intensive and suffers heavily from sampling errors. To effect change, we have hypothesized a sub-diffuse optical tomography modality that can identify the differences in depth sensitivity of the fluorescence, Cetuximab-IRDye800CW conjugate (ICON), by the fluorescent photons collected from sub-diffused media as a fun...
Journal of Biological Chemistry, 2014
Background: High affinity human plasminogen (hPg) binding to Group A Streptococcus (GAS) is media... more Background: High affinity human plasminogen (hPg) binding to Group A Streptococcus (GAS) is mediated by the coiledcoil M-like protein, PAM. Results: Amino acid residues in the a1a2 domain of PAM direct high affinity PAM/hPg binding regardless of oligomerization status of PAM. Conclusion: The a1a2 domain defines its hPg binding site, regardless of PAM dimerization. Significance: The virulence of GAS is altered by mutations in PAM(a1a2). A emm53 subclass of Group A Streptococcus pyogenes (GAS) interacts tightly with human plasma plasminogen (hPg) and plasmin (hPm) via the kringle 2 (K2 hPg) domain of hPg/hPm and the N-terminal a1a2 regions of a GAS coiled-coil M-like protein (PAM). Previous studies have shown that a monomeric PAM fragment, VEK30 (residues 97-125 ؉ Tyr), interacted specifically with isolated K2 hPg. However, the binding strength of VEK30 (K D ؍ 56 nM) was ϳ60-fold weaker than that of full-length dimeric PAM (K D ؍ 1 nM). To assess whether this attenuated binding was due to the inability of VEK30 to dimerize, we defined the minimal length of PAM required to dimerize using a series of peptides with additional PAM residues placed at the NH 2 and COOH termini of VEK30. VEK64 (PAM residues 83-145 ؉ Tyr) was found to be the smallest peptide that adopted an ␣-helical dimer, and was bound to K2 hPg with nearly the same affinity as PAM (K D ؍ 1-2 nM). However, addition of two PAM residues (Arg 126-His 127) to the COOH terminus of VEK30 (VEK32) maintained a monomeric peptidic structure, but exhibited similar K2 hPg binding affinity as full-length dimeric PAM. We identified five residues in a1a2 (Arg 113 , His 114 , Glu 116 , Arg 126 , His 127), mutation of which reduced PAM binding affinity for K2 hPg by ϳ1000-fold. Replacement of these critical residues by Ala in the GAS genome resulted in reduced virulence, similar to the effects of inactivating the PAM gene entirely. We conclude that rather than dimerization of PAM, the five key residues in the binding domain of PAM are essential to mediate the high affinity interaction with hPg, leading to increased GAS virulence. More than 200 M-protein-based serotypes of Group A Streptococcus pyogenes (GAS) 2 exist that cause Ͼ700 million cases of human pharyngeal and dermal infections worldwide each year. These infections range from non-invasive pharyngitis and impetigo, to severe and treatment-resistant forms of infectious diseases, e.g. necrotizing fasciitis and streptococcal toxic shock syndrome, as well as postinfectious nonpyogenic diseases, e.g. rheumatic fever and glomuleronephritis. Because of the existence of these latter highly virulent strains of GAS, which lead to high morbidity and oftentimes death, virulence factors of GAS have been sought for vaccine development as a global health issue. All GAS strains contain a form of a surface-resident M-protein, which is housed in a virulence operon of GAS under control of the multiple gene activator, mga (1). A subset of these M-proteins present in skin-tropic highly virulent strains of GAS bind with high affinity to host human plasma plasminogen (hPg), and this interaction is a critical determinant of the virulence of these strains (2). All GAS strains secrete a hPg activator, streptokinase, which, through a series of steps, converts GAS-bound hPg to the serine protease, plasmin (hPm) (3). The hPm remains bound to GAS, thus providing GAS to a proteolytic surface. This feature enables GAS to degrade encapsulating fibrin and, directly or indirectly, extracellular matrix proteins, thereby encouraging higher infectivity and systemic dissemination of the bacteria (4). The noncatalytic chain of hPm and corresponding regions of hPg contain five ϳ80 residue triple disulfide-linked kringle (K) domains (5). The main functions of kringle motifs are to mediate the binding of hPg to activation effectors and bind to relevant receptors and other proteins. Chief among the ligands for kringles is Lys and Lys analogues, with K1 hPg , K4 hPg , and K5 hPg showing highest affinity for Lys. K2 hPg possesses the lowest Lys binding strength for Lys binding kringles (6-9) and K3 hPg does not possess a binding site for Lys (10). The physiological role for
... Thank you for sticking with me during my need. I would like to thank Dr. Shreemanta K. Parida... more ... Thank you for sticking with me during my need. I would like to thank Dr. Shreemanta K. Parida, Dr. Mayuri Pandu and Subhamay Bhattacharya for patiently bearing my occasional bouts of frustration and their encouragement and support. ...
Journal of biomedicine & biotechnology, 2012
In order for invasive pathogens to migrate beyond the site of infection, host physiological barri... more In order for invasive pathogens to migrate beyond the site of infection, host physiological barriers such as the extracellular matrix, the basement membrane, and encapsulating fibrin network must be degraded. To circumvent these impediments, proteolytic enzymes facilitate the dissemination of the microorganism. Recruitment of host proteases to the bacterial surface represents a particularly effective mechanism for enhancing invasiveness. Plasmin is a broad spectrum serine protease that degrades fibrin, extracellular matrices, and connective tissue. A large number of pathogens express plasminogen receptors which immobilize plasmin(ogen) on the bacterial surface. Surface-bound plasminogen is then activated by plasminogen activators to plasmin through limited proteolysis thus triggering the development of a proteolytic surface on the bacteria and eventually assisting the spread of bacteria. The host hemostatic system plays an important role in systemic infection. The interplay between ...
Journal of Biological Chemistry, 2014
Background: High affinity human plasminogen (hPg) binding to Group A Streptococcus (GAS) is media... more Background: High affinity human plasminogen (hPg) binding to Group A Streptococcus (GAS) is mediated by the coiledcoil M-like protein, PAM. Results: Amino acid residues in the a1a2 domain of PAM direct high affinity PAM/hPg binding regardless of oligomerization status of PAM. Conclusion: The a1a2 domain defines its hPg binding site, regardless of PAM dimerization. Significance: The virulence of GAS is altered by mutations in PAM(a1a2).
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Papers by Sarbani Bhattacharya