INTRODUCTION
L-phenylalanine ammonia-lyase (PAL; EC 4.3.1.5) catalyzes the reaction of reverse deamination of L-phenylalanine to trans-cinnamic acid and ammonia [1]. It is the key enzyme of phenylpropanoid metabo-lism in plant and fungi, where it is involved in biosynthesis of secondary metabolites (flavonoids, furanocoumarines, and cell wall components), existing in multiple isoforms [2, 3].
PAL plays an important role in catabolic processes of microorganisms, providing for utilization of L-phenylalanine as a sole source of carbon and nitrogen [4]. Among the microorganisms, the highest PAL activity is exhibited by yeasts, especially the red basidiomycetes of the Rhodotorula family [5]. Sporobolomyces roseus and Sporidiobolus pararoseus are also PAL-producing yeasts [6].
Therapeutic potential of PAL with respect to neoplasms was evaluated due to its selective activity to phenylalanine and amino acids that are consumed by mammalian cells from external sources. PAL was shown to inhibit neoplasm growth in vitro [7].
The enzyme is also of interest as a therapeutic agent for phenylketonuria treatment and may be used for both direct therapy of phenylketonuria and production of food products free of phenylalanine [8]. Besides the medical applications, the enzyme may be used in biotechnology for L-phenylalanine production from trans-cinnamic acid [9].
Considerable contribution to the development and assimilation of the technology of specialized food products was made by G.B. Gavrilov, N.B. Gavrilova, V.I. Ganina, N.I. Dunchenko, I.A. Evdokimov, V.I. Kruglik, K.S. Ladodo, L.A. Ostroumov, A.N. Petrov, V.O. Popov, G.Yu. Sazhinov, V.A. Tutel'yan, V.D. Kharitonov, I.S. Khamagaeva, and A.G. Khramtsov, and to the technology of the enzyme preparation of PAL, by V.I. Mushtaev, M. Jason Мас Donald, H. Orum, and O.F. Rasmussen.
The development of new and improvement of existing technologies of the PAL preparation production requires new, more intensive sources of its superexpression, which is impossible without studies on the specific features of its genetics in known producers. Only 26 sequences of genomes of microorganisms exhibiting PAL activity were found in the databases of genetic sequences (EMBL and GenBank). Therefore, the search for microorganisms exhibiting L-phenylalanine ammonia-lyase activity based on sequence analysis of their genomes is urgent.
The aim of the work was to screen and identify pigmented yeasts producing L-phenylalanine ammonia-lyase and describe their physiological and biochemical characteristics.
