scholarly journals Role of Non-Active-Site Residue Trp-93 in the Function and Stability of New Delhi Metallo-β-Lactamase 1

2015 ◽  
Vol 60 (1) ◽  
pp. 356-360 ◽  
Author(s):  
Asad U. Khan ◽  
M. Tabish Rehman
Keyword(s):  
Active Site ◽  
Catalytic Efficiency ◽  
Structure And Function ◽  
Clinical Strain ◽  
New Delhi ◽  
Active Site Residue ◽  
Active Site Residues ◽  
Content Type ◽  
And Function

ABSTRACTNew Delhi metallo-β-lactamase-1 (NDM-1) is expressed by various members ofEnterobacteriaceaeas a defense mechanism to hydrolyze β-lactam antibiotics. Despite various studies showing the significance of active-site residues in the catalytic mechanism, there is a paucity of reports addressing the role of non-active-site residues in the structure and function of NDM-1. In this study, we investigated the significance of non-active-site residue Trp-93 in the structure and function of NDM-1. We clonedblaNDM-1from anEnterobacter cloacaeclinical strain (EC-15) and introduced the mutation of Trp-93 to Ala (yielding the Trp93Ala mutant) by PCR-based site-directed mutagenesis. Proteins were expressed and purified to homogeneity by affinity chromatography. The MICs of the Trp93Ala mutant were reduced 4- to 8-fold for ampicillin, cefotaxime, ceftazidime, cefoxitin, imipenem, and meropenem. The poor hydrolytic activity of the Trp93Ala mutant was also reflected by its reduced catalytic efficiency. The overall catalytic efficiency of the Trp93Ala mutant was reduced by 40 to 55% (theKmwas reduced, while thekcatwas similar to that of wild-type NDM-1 [wtNDM-1]). Heat-induced denaturation showed that the ΔGDoandTmof Trp93Ala mutant were reduced by 1.8 kcal/mol and 4.8°C, respectively. Far-UV circular dichroism (CD) analysis showed that the α-helical content of the Trp93Ala mutant was reduced by 2.9%. The decrease in stability and catalytic efficiency of the Trp93Ala mutant was due to the loss of two hydrogen bonds with Ser-63 and Val-73 and hydrophobic interactions with Leu-65, Val-73, Gln-123, and Asp-124. The study provided insight into the role of non-active-site amino acid residues in the hydrolytic mechanism of NDM-1.

The key role of a non-active-site residue Met148 on the catalytic efficiency of meta-cleavage product hydrolase BphD

2013 ◽  
Vol 97 (24) ◽  
pp. 10399-10411 ◽  
Author(s):  
Hao Zhou ◽  
Yuanyuan Qu ◽  
Chunlei Kong ◽  
E. Shen ◽  
Jingwei Wang ◽  
...  
Keyword(s):  
Active Site ◽  
Catalytic Efficiency ◽  
Cleavage Product ◽  
Active Site Residue

Structure and function: organization of a medical specialty for the rest of the 20th century

1982 ◽  
Vol 57 (3) ◽  
pp. 301-308 ◽  
Author(s):  
W. Kemp Clark
Keyword(s):  
20Th Century ◽  
American Association ◽  
Medical Specialty ◽  
Structure And Function ◽  
Concerted Effort ◽  
Content Type ◽  
The Past ◽  
And Function ◽  
Fine Print

✓ The President of the American Association of Neurological Surgeons concentrates on the problems facing the specialty, the achievements of the past, and the mechanisms designed to foster the advancement and role of neurosurgery. To counter the difficult days ahead, he emphasizes the need for concerted effort and action on the part of neurosurgeons within the umbrella of the Association as spokesman for the specialty and advocate for the patients' welfare.

Essential role of the disintegrin-like domain in ADAMTS13 function

Blood ◽  
2009 ◽  
Vol 113 (22) ◽  
pp. 5609-5616 ◽  
Author(s):  
Rens de Groot ◽  
Ajoy Bardhan ◽  
Nalisha Ramroop ◽  
David A. Lane ◽  
James T. B. Crawley
Keyword(s):  
Active Site ◽  
Catalytic Efficiency ◽  
Targeted Mutagenesis ◽  
Fold Reduction ◽  
Scissile Bond ◽  
And Function ◽  
Von Willebrand ◽  
A2 Domain ◽  
Willebrand Factor

ADAMTS13 is a highly specific multidomain plasma metalloprotease that regulates the multimeric size and function of von Willebrand factor (VWF) through cleavage at a single site in the VWF A2 domain. The precise role that the ADAMTS13 disintegrin-like domain plays in its function remains uncertain. Truncated ADAMTS13 variants suggested the importance of the disintegrin-like domain for both enzyme activity and specificity. Targeted mutagenesis of nonconserved regions (among ADAMTS family members) in the disintegrin-like domain identified 3 of 8 ADAMTS13 mutants (R349A, L350G, V352G) with reduced proteolytic activity. Kinetic analyses revealed a 5- to 20-fold reduction in catalytic efficiency of VWF115 (VWF residues 1554-1668) proteolysis by these mutants. These residues form a predicted exposed exosite on the surface of the disintegrin-like domain that lies approximately 26 Å from the active site. Kinetic analysis of VWF115 carrying the D1614A mutation suggested that Arg349 in the ADAMTS13 disintegrin-like domain interacts directly with Asp1614 in VWF A2. We hypothesize that this interaction assists in positioning the scissile bond within the active site of ADAMTS13 and therefore plays a major role in determining cleavage parameters (Km and kcat), as opposed to binding affinity (Kd) of ADAMTS13 for VWF, the latter being primarily determined by the spacer domain.

scholarly journals Essential Role of Septin 7 in Skeletal Muscle Structure and Function

2020 ◽  
Vol 118 (3) ◽  
pp. 258a
Author(s):  
Laszlo Csernoch ◽  
Mónika Gönczi ◽  
Zsolt Ráduly ◽  
László Szabó ◽  
Nóra Dobrosi ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Essential Role ◽  
Structure And Function ◽  
Muscle Structure ◽  
And Function

scholarly journals Effects of Dysbiosis and Dietary Manipulation on the Digestive Microbiota of a Detritivorous Arthropod

2021 ◽  
Vol 9 (1) ◽  
pp. 148
Author(s):  
Marius Bredon ◽  
Elisabeth Depuydt ◽  
Lucas Brisson ◽  
Laurent Moulin ◽  
Ciriac Charles ◽  
...  
Keyword(s):  
Crucial Role ◽  
Structure And Function ◽  
Ecological Interactions ◽  
Dietary Manipulation ◽  
Biotic Factors ◽  
Abiotic And Biotic Factors ◽  
And Function ◽  
Multicellular Organisms ◽  
Over Time

The crucial role of microbes in the evolution, development, health, and ecological interactions of multicellular organisms is now widely recognized in the holobiont concept. However, the structure and stability of microbiota are highly dependent on abiotic and biotic factors, especially in the gut, which can be colonized by transient bacteria depending on the host’s diet. We studied these impacts by manipulating the digestive microbiota of the detritivore Armadillidium vulgare and analyzing the consequences on its structure and function. Hosts were exposed to initial starvation and then were fed diets that varied the different components of lignocellulose. A total of 72 digestive microbiota were analyzed according to the type of the diet (standard or enriched in cellulose, lignin, or hemicellulose) and the period following dysbiosis. The results showed that microbiota from the hepatopancreas were very stable and resilient, while the most diverse and labile over time were found in the hindgut. Dysbiosis and selective diets may have affected the host fitness by altering the structure of the microbiota and its predicted functions. Overall, these modifications can therefore have effects not only on the holobiont, but also on the “eco-holobiont” conceptualization of macroorganisms.

scholarly journals Neuroplacentology in congenital heart disease: placental connections to neurodevelopmental outcomes

2021 ◽  
Author(s):  
Rachel L. Leon ◽  
Imran N. Mir ◽  
Christina L. Herrera ◽  
Kavita Sharma ◽  
Catherine Y. Spong ◽  
...  
Keyword(s):  
Brain Development ◽  
Congenital Heart ◽  
Fetal Brain ◽  
In Utero ◽  
Structure And Function ◽  
Brain Growth ◽  
Neurodevelopmental Outcomes ◽  
Fetal Brain Development ◽  
And Function

Abstract Children with congenital heart disease (CHD) are living longer due to effective medical and surgical management. However, the majority have neurodevelopmental delays or disorders. The role of the placenta in fetal brain development is unclear and is the focus of an emerging field known as neuroplacentology. In this review, we summarize neurodevelopmental outcomes in CHD and their brain imaging correlates both in utero and postnatally. We review differences in the structure and function of the placenta in pregnancies complicated by fetal CHD and introduce the concept of a placental inefficiency phenotype that occurs in severe forms of fetal CHD, characterized by a myriad of pathologies. We propose that in CHD placental dysfunction contributes to decreased fetal cerebral oxygen delivery resulting in poor brain growth, brain abnormalities, and impaired neurodevelopment. We conclude the review with key areas for future research in neuroplacentology in the fetal CHD population, including (1) differences in structure and function of the CHD placenta, (2) modifiable and nonmodifiable factors that impact the hemodynamic balance between placental and cerebral circulations, (3) interventions to improve placental function and protect brain development in utero, and (4) the role of genetic and epigenetic influences on the placenta–heart–brain connection. Impact Neuroplacentology seeks to understand placental connections to fetal brain development. In fetuses with CHD, brain growth abnormalities begin in utero. Placental microstructure as well as perfusion and function are abnormal in fetal CHD.

scholarly journals Endogenous Mammalian Cardiotonic Steroids—A New Cardiovascular Risk Factor?—A Mini-Review

Life ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 727
Author(s):  
Natalia Słabiak-Błaż ◽  
Grzegorz Piecha
Keyword(s):  
Adenosine Triphosphatase ◽  
Therapeutic Strategies ◽  
Structure And Function ◽  
Sodium Potassium ◽  
Sodium Homeostasis ◽  
Cardiovascular Tissue ◽  
Ancient Times ◽  
And Function ◽  
Regulation Of Blood Pressure

The role of endogenous mammalian cardiotonic steroids (CTS) in the physiology and pathophysiology of the cardiovascular system and the kidneys has interested researchers for more than 20 years. Cardiotonic steroids extracted from toads or plants, such as digitalis, have been used to treat heart disease since ancient times. CTS, also called endogenous digitalis-like factors, take part in the regulation of blood pressure and sodium homeostasis through their effects on the transport enzyme called sodium–potassium adenosine triphosphatase (Na/K-ATPase) in renal and cardiovascular tissue. In recent years, there has been increasing evidence showing deleterious effects of CTS on the structure and function of the heart, vasculature and kidneys. Understanding the role of CTS may be useful in the development of potential new therapeutic strategies.

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