A Novel Protein-Deamidating Enzyme from Chryseobacterium proteolyticum sp. nov., a Newly Isolated Bacterium from Soil

Abstract

A novel protein-deamidating enzyme, which has potential for industrial applications, was purified from the culture supernatant of Chryseobacterium proteolyticum strain 9670 T isolated from rice field soil in Tsukuba, Japan. The deamidating activities on carboxybenzoxy (Cbz)-Gln-Gly and caseins and protease activity were produced synchronously by the isolate. Both deamidating activities were eluted as identical peaks separated from several proteases by phenyl-Sepharose chromatography of the culture supernatant. The enzyme catalyzed the deamidation of native caseins with no protease and transglutaminase activities. Phenotypic characterization and DNA analyses of the isolate were performed to determine its taxonomy. Physiological and biochemical characteristics, 16S rRNA gene sequence analysis, and DNA-DNA relatedness data indicated that the isolate should be placed as a new species belonging to the genus Chryseobacterium. The isolate showed no growth on MacConkey agar and produced acid from sucrose. The levels of DNA-DNA relatedness between the isolate and other related strains were less than 17%. The name Chryseobacterium proteolyticum is proposed for the new species; strain 9670 is the type strain (‫؍‬FERM P-17664).An enzyme catalyzing deamidation of proteins has a great potential for industrial applications. Deamidation of proteins can improve protein functionalities such as solubility, emulsification, and foaming and gelation properties, which are desired properties in some food proteins. Most plant proteins have poor solubility and functionality under mild acidic conditions, which are the pH ranges of most food systems, resulting in their limited use in foods. Because the contents of glutamine residue in plant proteins are generally high, deamidation of such proteins is one of the most promising ways to expand their uses and to improve their functionalities. Many studies of the chemical (mild acid or alkaline treatment) or physical (dry heat treatment) deamidation of food proteins had reported and demonstrated the effectiveness of deamidation for improvement of protein functionalities (see reference 25 for review). To avoid unfavorable side effects brought about by nonenzymatic treatments-for example, concomitant peptide bond cleavage, off-flavor formation, and amino acid racemization-enzymatic deamidations of proteins have been examined (see reference 10 for review). Protease (16), transglutaminase (23), and peptidoglutaminase (9) were used for this purpose. None of their primary reactions were deamidations, or the enzymic substrates were peptides rather than proteins. Besides the improvement in protein functionalities, protein-deamidating enzymes could be used for many applications, including protein structure analysis.In 1971, Kikuchi et al. (17) found an enzyme, peptidoglutaminase, from Bacillus circulans that deamidates the peptidebound glutamines. This enzyme was not active on high-molecular-weight peptides, i.e., proteins such as caseins, unless the proteins were hydrolyzed to short peptides (17). In p...

Transfer of Chryseobacterium meningosepticum and Chryseobacterium miricola to Elizabethkingia gen. nov. as Elizabethkingia meningoseptica comb. nov. and Elizabethkingia miricola comb. nov.

“…At that time the genera Chryseobacterium (including six species previously considered Flavobacterium species, Chryseobacterium balustinum, Chryseobacterium gleum, Chryseobacterium indologenes, Chryseobacterium indoltheticum, Chryseobacterium meningosepticum and Chryseobacterium scophthalmum), Bergeyella (including a single species, Bergeyella zoohelcum, previously considered a Weeksella species) and Riemerella (including a single species, Riemerella anatipestifer, long considered a Moraxella species) composed a separate rRNA branch of the family Flavobacteriaceae in rRNA superfamily V. Although 'Chryseobacterium proteolyticum' (Yamaguchi & Yokoe, 2000), Chryseobacterium defluvii (Kämpfer et al, 2003), Chryseobacterium joostei (Hugo et al, 2003), Chryseobacterium miricola (Li et al, 2003) and Riemerella columbina (Vancanneyt et al, 1999) have been described since then, the Chryseobacterium-Bergeyella-Riemerella (CBR) branch retains its original taxonomic position.…”

Chryseobacterium taiwanense sp. nov., isolated from soil in Taiwan

“…Two additional species were recently transferred to the new genus Elizabethkingia (Kim et al, 2005). The name of the protein-deaminating taxon 'Chryseobacterium proteolyticum' (Yamaguchi & Yokoe, 2000) was not validly published under the Rules of the Bacteriological Code (1990 Revision) (Lapage et al, 1992).…”

“…The patent strain 'C. proteolyticum' FERM P-17664 was included in the study using data from the NCBI database and literature (Yamaguchi & Yokoe, 2000).…”

Gaetbulibacter aestuarii sp. nov., isolated from shallow coastal seawater, and emended description of the genus Gaetbulibacter

“…Growth in an anaerobic chamber (CO 2 /H 2 /N 2 , 10 : 10 : 80; Sheldon Manufacturing) was assessed on MA for 1 week. Acid production from glucose and maltose was tested as described by Yamaguchi & Yokoe (2000). The presence of flexirubin-type pigments was determined by the bathochromatic shift test using 20 % (w/v) KOH (Bernardet et al, 2002;McCammon & Bowman, 2000).…”