Essay Example on Leptin is a versatile hormone that regulates several Metabolic









Leptin is a versatile hormone that regulates several metabolic pathways such as controlling body weight feed intake energy expenditure immune function and reproduction In spite of exhaustive studies that performed on the bovine LEP gene no attempt has been made to comprehensively and systematically analyze its entire coding SNPs The present study was carried out to identify the most deleterious non synonymous SNPs nsSNPs of bovine LEP gene To predict the possible impact of missense mutations on leptin structure and function SNPs data that obtained from dbSNP database were analyzed using various bioinformatics tools The total nsSNPs that considered for the present study were 28 It was found that 9 nsSNPs including R66M H91N H91P A104V S162P D186Y D186G C191S and C191G in 6 amino acid positions were found to be deleterious and damaging by four common nsSNPs prediction tools and thus affecting leptin protein structure and biological activity I Mutant 2 eliminated two nsSNPs including S12P and D16Y since they increase protein stability upon mutation Further information regarding the residual deleterious nsSNPs showed that three of these variants including R66M C191S and C191G were confirmed that they were located in very high conserved positions and thus the mutations in these amino acids positions have deleterious evolutionary consequences The findings of the present study proved that R66M C191S and C191G nsSNPs have the most considerable deleterious consequences on both structure and function of bovine leptin 

The present study provides the first comprehensive computation of the effect of the most damaging nsSNPs on both structure and function of bovine leptin Exploration of these mutations may provide novel perspectives for various production traits associated features Keywords bovine computational analysis leptin non synonymous SNPs Introduction One of the most prominent hormones that provide hotspot indicators for numerous metabolic traits of cattle is leptin Leptin is a hormone that regulates the body weight by maintaining the balance between food intake and energy expenditure through signaling to the brain to change the stored energy levels Zhou et al 2009 It plays a crucial role in the regulation of feed and energy metabolism of cattle Liefers et al 2005 In addition to the obvious role of leptin in controlling appetite it has other noticeable roles in regulating growth reproduction body composition and immunity Leptin is encoded by a LEP gene which is accommodated a size of about 20kb It consists of three exons separated by two introns and the exons for the LEP gene cover about 15kb of the bovine genome Actually the first exon is truncated in the mature blood circulating hormone Meanwhile the rest two exons produce the fully mature 167 residues by excising the first 24 signal amino acid residues to produce 16kd of blood circulating leptin Liefers 2004 Leptin contains a distinctive three dimensional 3 D four α helix bundle structure of A B C D pattern Kline et al 1997 This structure is arranged in a four sequentially similar anti parallel left hand twisted α helices bundle that are connected by two crossover links along with one short loop Gutierrez et al 2009 In addition to the four main helices an extra fragment that known as helix E which is a distorted short helix is also presented on the structure 

The helix E is found in the loop linking between both helices C and D Leptin contains a single disulfide bond that links two cysteine residues Cys141 and Cys191 within the C and D helices to form a unique kink This kinked helix that connects the last turn of the α helix D to a loop that extends from the C to D helix has been proven to be very crucial for the structural integrity and stability of leptin Rock et al 1996 Hence any missense mutation that changes this highly organized 3D structure of leptin may have deleterious outcomes on many critical metabolic pathways this hormone is involved in On the other hand it was obviously demonstrated that many SNPs have functional effects on their corresponding protein structure either by a single change in the amino acid Al Shuhaib et al 2017 or by substituting the transcription factors Liao and Lee 2010 or by other means Synonymous or silent mutations are now widely acknowledged to be able to cause changes in protein expression conformation and function Sauna and Kimchi Sarfaty 2011 However mutations in introns and other non coding regions do not alter amino acid sequences Conversely a non synonymous single nucleotide polymorphism nsSNP which is present within the exon of a gene is responsible for the incorporation of an alternative amino acid and known to be one of the main causes of the possible alterations of the leptin mode of action However each amino acid alteration has its own consequences regarding its position and identity in the 3D structure of leptin Accordingly it is important to differentiate these consequences computationally Through more than a decade several missense mutations have been discovered in this highly studied leptin protein Liefers et al 2003 De Matteis et al 2012 no comprehensive study was presented to predict the final consequences of the whole nsSNPs in this bovine hormone Therefore this study is designed to provide the first comprehensive computational prediction for the most deleterious missense mutations in the bovine leptin

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