scholarly journals Structure-Function Analysis of Immunity Proteins of Pediocin-Like Bacteriocins: C-Terminal Parts of Immunity Proteins Are Involved in Specific Recognition of Cognate Bacteriocins

2004 ◽  
Vol 70 (5) ◽  
pp. 2647-2652 ◽  
Author(s):  
Line Johnsen ◽  
Gunnar Fimland ◽  
Dimitris Mantzilas ◽  
Jon Nissen-Meyer
Keyword(s):  
Structure Function ◽  
Function Analysis ◽  
Cd Spectroscopy ◽  
Aqueous Environment ◽  
Specific Recognition ◽  
Function Relationship ◽  
Enterocin A ◽  
Relationship Of ◽  
High Degree ◽  
Strain Dependent

ABSTRACT The immunity proteins of pediocin-like bacteriocins show a high degree of specificity with respect to the pediocin-like bacteriocin they recognize and confer immunity to. The aim of this study was to identify regions of the immunity proteins that are involved in this specific recognition. Six different hybrid immunity proteins were constructed from three different pediocin-like bacteriocin immunity proteins that have similar sequences but confer resistance to different bacteriocins. These hybrid immunity proteins were then tested for their ability to confer immunity to various pediocin-like bacteriocins. The specificities of the hybrid immunity proteins proved to be similar to those of the immunity proteins from which the C-terminal halves were derived, thus revealing that the C-terminal half of immunity proteins for pediocin-like bacteriocins contains a domain that is involved in specific recognition of the bacteriocins they confer immunity to. Moreover, the results also revealed that the effectiveness of an immunity protein is strain dependent and that its functionality thus depends in part on interplay with strain-dependent factors. To further investigate the structure-function relationship of these immunity proteins, the enterocin A and leucocin A immunity proteins (EntA-im and LeuA-im) were purified to homogeneity and structurally analyzed under various conditions by Circular dichroism (CD) spectroscopy. The results revealed that both immunity proteins are α-helical and well structured in an aqueous environment, the denaturing temperature being 78.5°C for EntA-im and 58.0°C for LeuA-im. The CD spectra also revealed that there was no further increase in the structuring or α-helical content when the immunity proteins were exposed to dodecylphosphocholine micelles or dioleoyl-l-α-phosphatidyl-dl-glycerol (DOPG) liposomes, indicating that the immunity proteins, in contrast to the bacteriocins, do not interact extensively with membranes. They may nevertheless be loosely associated with the membrane, possibly as peripheral membrane proteins, thus enabling them to interact with their cognate bacteriocin.

Role of aromatic residues in the structure-function relationship of .alpha.-bungarotoxin

Biochemistry ◽  
1982 ◽  
Vol 21 (11) ◽  
pp. 2592-2600 ◽  
Author(s):  
Yee Hsiung Chen ◽  
Jang Chyi Tai ◽  
Wan Jen Huang ◽  
Ming Zong Lai ◽  
Mien Chie Hung ◽  
...  
Keyword(s):  
Structure Function ◽  
Aromatic Residues ◽  
Structure Function Relationship ◽  
Function Relationship ◽  
Alpha Bungarotoxin ◽  
Relationship Of

Gene cloning and structure - function relationship of cytokines such as TNF and interleukins

1987 ◽  
Vol 16 (3-4) ◽  
pp. 219-226 ◽  
Author(s):  
Walter Fiers ◽  
Rudi Beyaert ◽  
Peter Brouckaert ◽  
Bart Everaerdt ◽  
Guy Haegeman ◽  
...  
Keyword(s):  
Structure Function ◽  
Gene Cloning ◽  
Structure Function Relationship ◽  
Function Relationship ◽  
Relationship Of

scholarly journals Pleiotropic functions of the transmembrane domain 6 of human melanocortin-4 receptor

2012 ◽  
Vol 49 (3) ◽  
pp. 237-248 ◽  
Author(s):  
Hui Huang ◽  
Ya-Xiong Tao
Keyword(s):  
Cell Surface ◽  
Structure Function ◽  
Transmembrane Domain ◽  
Mapk Pathway ◽  
Surface Expression ◽  
Camp Signaling ◽  
Cell Surface Expression ◽  
Melanocortin 4 Receptor ◽  
Function Relationship ◽  
Relationship Of

The melanocortin-4 receptor (MC4R) is a critical regulator of energy homeostasis and has emerged as a premier target for obesity treatment. Numerous mutations in transmembrane domain 6 (TM6) of MC4R resulting in functional alterations have been identified in obese patients. Several mutagenesis studies also provided some data suggesting the importance of this domain in receptor function. To gain a better understanding of the structure–function relationship of the receptor, we performed alanine-scanning mutagenesis in TM6 to determine the functions of side chains. Of the 31 residues, two were important for cell surface expression, five were indispensable for α-melanocyte-stimulating hormone (α-MSH) and β-MSH binding, and six were important for signaling in the Gs–cAMP–PKA pathway. H264A, targeted normally to the plasma membrane, was undetectable by competitive binding assay and severely defective in basal and stimulated cAMP production and ERK1/2 phosphorylation. Nine mutants had decreased basal cAMP signaling. Seven mutants were constitutively active in cAMP signaling and their basal activities could be inhibited by two MC4R inverse agonists, Ipsen 5i and ML00253764. Five mutants were also constitutively active in the MAPK pathway with enhanced basal ERK1/2 phosphorylation. In summary, our study provided comprehensive data on the structure–function relationship of the TM6 of MC4R. We identified residues that are important for cell surface expression, ligand binding, cAMP generation, and residues for maintaining the WT receptor in active conformation. We also reported constitutive activation of the MAPK pathway and biased signaling. These data will be useful for rationally designing MC4R agonists and antagonists for treatment of eating disorders.

scholarly journals Distribution and Structure-Function Relationship of Myosin Heavy Chain Isoforms in the Adult Mouse Heart

2007 ◽  
Vol 282 (33) ◽  
pp. 24057-24064 ◽  
Author(s):  
Maike Krenz ◽  
Sakthivel Sadayappan ◽  
Hanna E. Osinska ◽  
Jeffrey A. Henry ◽  
Samantha Beck ◽  
...  
Keyword(s):  
Structure Function ◽  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Adult Mouse ◽  
Myosin Heavy Chain Isoforms ◽  
Mouse Heart ◽  
Structure Function Relationship ◽  
Function Relationship ◽  
Relationship Of
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