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Med Hypotheses

Title:		Hormone fatty acid modifications: gram negative bacteria and vertebrates demonstrate common structure and function
Author(s):		Tizzano M; Sbarbati A;
Address:		"Department of Morphological-Biomedical Sciences, Section of Anatomy and Histology, University of Verona, Strade le Grazie, 8, 37134 Verona, Italy. taitiz1@hotmail.com"
Journal Title:		Med Hypotheses
Year:		2006
Volume:		20060427
Issue:		3
Page Number:		513 - 516
DOI:		10.1016/j.mehy.2006.03.010
ISSN/ISBN:		0306-9877 (Print) 0306-9877 (Linking)
Abstract:		"Bacteria are known to regulate diverse physiological processes through a mechanism called quorum sensing (QS). Prokaryotes communicate by extracellular signalling compounds, i.e. autoinducers (acyl homoserine lactone, AHL of Gram negative bacteria) or pheromones (post-translationally modified peptides of Gram positive bacteria), which activate genetic pathways when they reach a sufficient concentration (QS). A large number of Gram-negative quorum-sensing systems studied so far utilize N-acyl homoserine lactones as signal molecules. In vertebrates small synthetic molecules called growth hormone secretagogues (GHSs) stimulate the release of growth hormone (GH) from the pituitary. GH release is stimulated by hypothalamic GH-releasing hormone (GHRH) and ghrelin (endogenous ligand of the GHS-receptor, GHS-R). Ghrelin is a 28-amino acid peptide, in which the serine-3 (Ser3) is n-octanoylated, and this modification is essential for ghrelin's activity. Ghrelin is the first known case of a peptide hormone modified by a fatty acid. The major active form of ghrelin is a 28-amino acid peptide with octanoylated Ser3; one of the more represented bacterial autoinducers is the N-Octanoyl-DL-homoserine lactone (C8-HL) molecule. The authors hypothesize that Gram-negative bacteria and vertebrates have a functional similarity in the search of food and an important structural homology of AHL and ghrelin for the highly conserved Serine-acylated motive in both molecules. Our suggestions could help one to understand the convergent origin and the biologic meaning of the Serine-acylated group in these organisms, a biologic meaning very important due to the high conservation in two kingdoms which are so different"
Keywords:		"Amino Acid Sequence Animals Fatty Acids/chemistry Ghrelin *Gram-Negative Bacteria Growth Hormone/*metabolism Models, Biological Molecular Sequence Data Peptide Hormones/*chemistry/genetics/metabolism/*physiology Pituitary Gland/metabolism Pituitary Hormon;"
Notes:		"MedlineTizzano, Marco Sbarbati, Andrea eng Comparative Study 2006/04/29 Med Hypotheses. 2006; 67(3):513-6. doi: 10.1016/j.mehy.2006.03.010. Epub 2006 Apr 27"