Current Medicinal Chemistry             Send Orders for Reprints to reprints@benthamscience.ae 1772 Current Medicinal Chemistry, 2017, 24, 1772-1787 REVIEW ARTICLE Plant Pathogenesis-Related Proteins PR-10 and PR-14 as Components of Innate Immunity System and Ubiquitous Allergens Ekaterina I. Finkina, Daria N. Melnikova, Ivan V. Bogdanov and Tatiana V. Ovchinnikova * M.M.Shemyakin and Yu.A.Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya str., 16/10, 117997 Moscow, Russia A R T I C L E H I S T O R Y Received: May 25, 2016 Revised: September 23, 2016 Accepted: October 04, 2016 DOI: 10.2174/09298673236661610261 54111 Abstract: Pathogenesis-related (PR) proteins are components of innate immunity system in plants. They play an important role in plant defense against pathogens. Lipid transfer proteins (LTPs) and Bet v 1 homologs comprise of two separate families of PR-proteins. Both LTPs (PR-14) and Bet v 1 homologs (PR-10) are multifunctional small proteins involving in plant response to abiotic and biotic stress conditions. The representatives of these PR-protein fami- lies do not show any sequence similarity but have other common biochemical features such as low molecular masses, the presence of hydrophobic cavities, ligand binding properties, and antimicrobial activities. Besides, many members of PR-10 and PR-14 families are ubiquitous plant panallergens which are able to cause sensitization of human immune system and cross- reactive allergic reactions to plant food and pollen. This review is aimed at comparative analysis of structure-functional and allergenic properties of the PR-10 and PR-14 families, as well as prospects for their medicinal application. Keywords: Innate immunity system, pathogenesis-related proteins, plant defense, Bet v 1 homologs, lipid transfer proteins, ligand binding, allergens, cross reactivity. 1. INTRODUCTION Pathogenic microorganisms are ubiquitous in the environment. Resistance to pathogens is a prerequisite for survival of species. Although plants lack an adap- tive immune system, during evolution they have ac- quired a number of effective defense mechanisms pro- tecting them from environmental stress. Plants have such defense strategies of innate immunity system as hypersensitive response (HR), cell wall thickening, in- creasing concentrations of phytohormones, induction of synthesis of antimicrobial peptides (AMPs) and low molecular weight secondary metabolites, as well as pathogenesis-related proteins (PR-proteins) and finally development of local or systemic acquired resistance (LAR or SAR) [1, 2]. During the attack of phytopatho- gens a set of different AMPs and PR-proteins as well as low molecular weight secondary metabolites are syn- thesized in plants. Most of the PR-proteins possess an- *Address correspondence to this author at the M.M.Shemyakin and Yu.A.Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya str., 16/10, 117997 Mos- cow, Russia; Tel: +7-495-336-44-44; E-mail: ovch@ibch.ru timicrobial activity, although mechanisms of their ac- tion often differ from that of AMPs. Combined interac- tions between PR-proteins greatly increase antimicro- bial effect, extend the repertoire of the suppressed pathogens, and compensate for the absence of adaptive immunity in plants. Stress-induced PR-proteins are divided into 17 families (PR1-17) in accordance with sequences simi- larity and biological activities. Many PR-proteins are constitutively expressed in different organs and tissues of plants, however induction of their synthesis takes place in response to abiotic or biotic stress [3]. Antimi- crobial PR-proteins affect the cell wall and plasma membrane of pathogens. Some of them have intracellu- lar targets or inhibit enzymes of microorganisms. Among representatives of PR-families are β-1,3- glucanases, chitinases, proteinase inhibitors, thaumatin- like proteins, peroxidases, defensins, thionins, oxalate oxidases, as well as Bet v 1 homologs (PR-10), and lipid transfer proteins (LTPs, PR-14) [3, 4]. The mem- bers of PR-10 and PR-14 protein families do not show any sequence similarity but have other common bio- 1875-533X/17 $58.00+.00 © 2017 Bentham Science Publishers