Mayuko Koreishi

CK2 phosphorylates Sec31 and regulates ER-To-Golgi trafficking.

Protein export from the endoplasmic reticulum (ER) is an initial and rate-limiting step of molecular trafficking and secretion. This is mediated by coat protein II (COPII)-coated vesicles, whose formation requires small GTPase Sar1 and 6 Sec proteins including Sec23 and Sec31. Sec31 is a component of the outer layer of COPII coat and has been identified as a phosphoprotein. The initiation and promotion of COPII vesicle formation is regulated by Sar1; however, the mechanism regulating the completion of COPII vesicle formation followed by vesicle release is largely unknown. Hypothesizing that the Sec31 phosphorylation may be such a mechanism, we identified phosphorylation sites in the middle linker region of Sec31. Sec31 phosphorylation appeared to decrease its association with ER membranes and Sec23. Non-phosphorylatable mutant of Sec31 stayed longer at ER exit sites and bound more strongly to Sec23. We also found that CK2 is one of the kinases responsible for Sec31 phosphorylation because CK2 knockdown decreased Sec31 phosphorylation, whereas CK2 overexpression increased Sec31 phosphorylation. Furthermore, CK2 knockdown increased affinity of Sec31 for Sec23 and inhibited ER-to-Golgi trafficking. These results suggest that Sec31 phosphorylation by CK2 controls the duration of COPII vesicle formation, which regulates ER-to-Golgi trafficking.

The Golgin Tether Giantin Regulates the Secretory Pathway by Controlling Stack Organization within Golgi Apparatus

Golgins are coiled-coil proteins that play a key role in the regulation of Golgi architecture and function. Giantin, the largest golgin in mammals, forms a complex with p115, rab1, GM130, and soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs), thereby facilitating vesicle tethering and fusion processes around the Golgi apparatus. Treatment with the microtubule destabilizing drug nocodazole transforms the Golgi ribbon into individual Golgi stacks. Here we show that siRNA-mediated depletion of giantin resulted in more dispersed Golgi stacks after nocodazole treatment than by control treatment, without changing the average cisternal length. Furthermore, depletion of giantin caused an increase in cargo transport that was associated with altered cell surface protein glycosylation. Drosophila S2 cells are known to have dispersed Golgi stacks and no giantin homolog. The exogenous expression of mammalian giantin cDNA in S2 cells resulted in clustered Golgi stacks, similar to the Golgi ribbon in mammalian cells. These results suggest that the spatial organization of the Golgi ribbon is mediated by giantin, which also plays a role in cargo transport and sugar modifications.

Ellagitannin oligomers and a neolignan from pomegranate arils and their inhibitory effects on the formation of advanced glycation end products

Two new ellagitannin oligomers, pomegraniins A (7, tetramer) and B (8, pentamer), and a new glucose ester of neolignan, pomegralignan (19), together with six known ellagitannins, were isolated from the arils and pericarps of Punica granatum L. (pomegranate). The structures of the new compounds were elucidated based on spectroscopic analyses and chemical evidence. The known ellagitannins included oligomers such as oenothein B (4), eucalbanin B (5), and eucarpanin T1 (6), in addition to the known ellagitannin monomers such as punicalagin (1), punicalin (2), and punicacortein C (3). This paper therefore represents the first report concerning the isolation of ellagitannin oligomers from pomegranate. Examination of the inhibitory activities of the polyphenolic constituents from pomegranate towards the formation of advanced glycation end products (AGEs) revealed that all ellagitannins tested were more potent inhibitors than aminoguanidine, which was used as a positive control, and pomegraniin A (7) showed the most potent effect.

Enzymatic Synthesis of β-Lactam Antibiotics and N-Fatty-Acylated Amino Compounds by the Acyl-Transfer Reaction Catalyzed by Penicillin V Acylase from Streptomyces mobaraensis

Penicillin V acylase from Streptomyces mobaraensis (Sm-PVA) showed high acyl-transfer activity in reactions using methyl esters of carboxylic acid (acyl donor) and amino compounds (nucleophile), to produce the corresponding amides. Moreover, Sm-PVA had broad substrate specificity, as indicated by the fact that it catalyzed the efficient synthesis of β-lactam antibiotics, capsaicin derivatives, and N-fatty-acyl-amino acid/N-fatty-acyl-peptide derivatives.

Purification and characterization of a novel aminoacylase from Streptomyces mobaraensis.

A novel aminoacylase was purified to homogeneity from culture broth of Streptomyces mobaraensis, as evidenced by SDS–polyacrylamide gel electrophoresis (PAGE). The enzyme was a monomer with an approximate molecular mass of 100 kDa. The purified enzyme was inhibited by the presence of 1,10-phenanthroline and activated by the addition of Co2+. It was stable at temperatures of up to 60 °C for 1 h at pH 7.2. It showed broad substrate specificity to N-acetylated L-amino acids. It catalyzed the hydrolysis of the amide bonds of various N-acetylated L-amino acids, except for Nε-acetyl-L-lysine and N-acetyl-L-proline. Hydrolysis of N-acetyl-L-methionine and N-acetyl-L-histidine followed Michaelis–Menten kinetics with K m values of 1.3±0.1 mM and 2.7±0.1 mM respectively. The enzyme also catalyzed the deacetylation of 7-aminocephalosporanic acid (7-ACA) and cephalosporin C. Moreover, feruloylamino acids and L-lysine derivatives of ferulic acid derivatives were synthesized in an aqueous buffer using the enzyme.

Efficient Nɛ-lauroyl-l-lysine production by recombinant ɛ-lysine acylase from Streptomyces mobaraensis

epsilon-Lysine acylase from Streptomyces mobaraensis (Sm-ELA), which specifically catalyzes hydrolysis of the epsilon-amide bond in various Nepsilon-acyl-L-lysines, was cloned and sequenced. The Sm-ELA gene consists of a 1617-bp open reading frame that encodes a 538-amino acid protein with a molecular mass of 55,816Da. An NCBI protein-protein BLAST search revealed that the enzyme belongs to the YtcJ-like metal-dependent amidohydrolase family, which is further characterized as the metallo-dependent hydrolase superfamily. The Sm-ELA gene was ligated into a pUC702 vector for expression in Streptomyces lividans TK24. Expression of recombinant Sm-ELA in S. lividans was approximately 300-fold higher than that in wild-type S. mobaraensis. The recombinant Sm-ELAs from the cell-free extract and culture supernatant were purified to homogeneity. The specific activities of the purified Sm-ELAs were 2500-2800U/mg, which were similar to that obtained for the wild-type Sm-ELA. Using the cell-free extract of the recombinant S. lividans cells, Nepsilon-lauroyl-L-lysine was synthesized from 500mM L-lysine hydrochloride and 50, 100, or 250mM lauric acid in an aqueous buffer solution at 37 degrees C. The yields were close to 100% after 6 and 9h of reaction for 50 and 100mM lauric acid, respectively, and 90% after 24h for 250mM lauric acid.

Purification, characterization, molecular cloning, and expression of a new aminoacylase from streptomyces mobaraensis that can hydrolyze N-(Middle/Long)-chain-fatty-acyl-L-amino acids as well as N-Short-chain-acyl-L- amino acids

We report here on the purification, characterization, molecular cloning, and expression of a new aminoacylase, initially isolated from the supernatant of Streptomyces mobaraensis (Sm-AA). Purified wild-type Sm-AA was found to be a monomeric protein with a molecular mass of 55 kDa. The cloned gene of Sm-AA contained an ORF of 1,383 bp, encoding a polypeptide of 460 amino acids. A BLAST search revealed that Sm-AA belongs to the peptidase M20 family, with identities to a hypothetical protein from Streptomyces pristinaespiralis, a putative peptidase from Streptomyces avermitilis, peptidase M20 from Frankia sp., succinyl-diaminopimelate desuccinylase from Hemophilus influenzae, and aminoacylase-1 from porcine kidney at 89, 88, 67, 29, and 25% respectively. The Sm-AA gene was subcloned into an expression vector, pSH19, and was expressed in Streptomyces lividans TK24. The amount of the recombinant Sm-AA expressed in the S. lividans cells was approximately 42-fold higher than that of Sm-AA found in the supernatant of S. mobaraensis. Sm-AA showed high hydrolytic activity towards various N-acetyl-L-amino acids and N-(middle/long)-chain-fatty-acyl-L-amino acids, with a preference for the acyl derivatives of L-Met, L-Ala, L-Cys, etc. with an optimum pH and temperature for reaction of about 7.5 and 50 °C (at pH 7.5).

Detection of in situ cleaved p115 with the cut specific antibodies in rapid protein inactivation system by tobacco etch viral protease cleavage

Correspondence: Ayano Satoh Graduate School of natural Science and Technology, Okayama university, Okayama, Japan Tel +81 86 251 8482 Fax +81 86 251 8705 Email ayano113@cc.okayama-u.ac.jp Abstract: Gene perturbation methods are commonly used in the study of gene and protein function. The authors of this paper recently developed a rapid protein inactivation technique utilizing tobacco etch virus (TEV)-derived protease. TEV protease recognizes the ENLYFQG (Glu-Asn-Leu-Tyr-Phe-Gln-Gly) amino acid sequence and specifically cleaves between Q and G. The authors developed antibodies that recognize the cleaved TEV (ENLYFQ) sequence, both in vitro and in vivo, but do not bind to uncleaved TEV (ENLYFQG). Using these antibodies, in situ protein cleavage was successfully detected. These antibodies used in combination with the TEV protease may be a useful complement to other perturbation methods.