scholarly journals Heme Binding to HupZ with a C-Terminal Tag from Group A Streptococcus

Molecules ◽  
2021 ◽  
Vol 26 (3) ◽  
pp. 549
Author(s):  
Ephrahime S. Traore ◽  
Jiasong Li ◽  
Tapiwa Chiura ◽  
Jiafeng Geng ◽  
Ankita J. Sachla ◽  
...  

HupZ is an expected heme degrading enzyme in the heme acquisition and utilization pathway in Group A Streptococcus. The isolated HupZ protein containing a C-terminal V5-His6 tag exhibits a weak heme degradation activity. Here, we revisited and characterized the HupZ-V5-His6 protein via biochemical, mutagenesis, protein quaternary structure, UV–vis, EPR, and resonance Raman spectroscopies. The results show that the ferric heme-protein complex did not display an expected ferric EPR signal and that heme binding to HupZ triggered the formation of higher oligomeric states. We found that heme binding to HupZ was an O2-dependent process. The single histidine residue in the HupZ sequence, His111, did not bind to the ferric heme, nor was it involved with the weak heme-degradation activity. Our results do not favor the heme oxygenase assignment because of the slow binding of heme and the newly discovered association of the weak heme degradation activity with the His6-tag. Altogether, the data suggest that the protein binds heme by its His6-tag, resulting in a heme-induced higher-order oligomeric structure and heme stacking. This work emphasizes the importance of considering exogenous tags when interpreting experimental observations during the study of heme utilization proteins.

2017 ◽  
Vol 75 (7) ◽  
Author(s):  
Xiaolan Zhang ◽  
Chunmei Lu ◽  
Fengmin Zhang ◽  
Yingli Song ◽  
Minghui Cai ◽  
...  

2020 ◽  
pp. 64-70
Author(s):  
Anastasiya Laknitskaya

Currently, one of the priority medical and social problems is the optimization of treatment methods for pyoderma associated with Streptococcus pyogenes — group A streptococcus (GAS). To date, the proportion of pyoderma, the etiological factor of which is Streptococcus pyogenes, is about 6 % of all skin diseases and is in the range from 17.9 to 43.9 % of all dermatoses. Role of the bacterial factor in the development of streptococcal pyoderma is obvious. Traditional treatment complex includes antibacterial drugs selected individually, taking into account the antibiotic sensitivity of pathognomonic bacteria, and it is not always effective. Currently implemented immunocorrection methods often do not take into account specific immunological features of the disease, the individual, and the fact that the skin performs the function of not only a mechanical barrier, but it is also an immunocompetent organ. Such an approach makes it necessary to conduct additional studies clarifying the role of factors of innate and adaptive immunity, intercellular mediators and antioxidant defense system, that allow to optimize the treatment of this pathology.


2020 ◽  
Vol 13 (12) ◽  
pp. e236800
Author(s):  
Grace Anne McCabe ◽  
Thomas Hardy ◽  
Thomas Gordon Campbell

A previously independent 56-year-old immunocompetent woman presented with septic shock in the setting of periorbital swelling and diffuse infiltrates on chest imaging. Blood cultures were positive for growth of group A Streptococcus (GAS). Broad spectrum antimicrobials were initiated with the inclusion of the antitoxin agent clindamycin. Necrosis of periorbital tissue was noted and surgical consultation was obtained. Débridement of both eyelids with skin grafting was performed. GAS was isolated from wound cultures and also observed on periorbital tissue microscopy. The final diagnosis was bilateral periorbital necrotising fasciitis (PONF) associated with invasive GAS infection. The patient had a prolonged intensive care unit course with input from multiple specialist teams. This case demonstrates the importance of early recognition and treatment of PONF, the profound systemic morbidity caused by these infections, and illustrates successful multidisciplinary teamwork.


2020 ◽  
Author(s):  
Sruti DebRoy ◽  
Victor Aliaga‐Tobar ◽  
Gabriel Galvez ◽  
Srishtee Arora ◽  
Xiaowen Liang ◽  
...  

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