Isolation and Biosynthesis of an Azoxyalkene Compound Produced by a Multiple Gene Disruptant of Streptomyces rochei

Streptomyces rochei 7434AN4 predominantly produces lankacidin and lankamycin under normal culture conditions, suggesting that other biosynthetic gene clusters for secondary metabolites are silent. To exploit silent metabolites of strain 7434AN4, we constructed mutant KA57, a multiple disruptant of the transcriptional repressor gene srrB together with the biosynthesis genes for both antibiotics. Mutant KA57 accumulated a compound (KA57-A) with a strong UV absorption at 235 nm, which was not detected in the parent strain or other mutants. Various spectroscopic analyses revealed that KA57-A is an azoxyalkene compound of a molecular formula of C10H20N2O3 with the R configuration at C-2. Biosynthesis of KA57-A was also studied by feeding with labeled acetates, amino acids, and 1-hexylamine. The hexenyl moiety (C1’-C6’) was derived from fatty acid, while the 3-amino-butan-1,2-diol moiety (C1-C4) was derived from C-2 of acetate (C1) and serine (C2-C4). Incorporation of [1,1-2H2]1-hexylamine indicated that C1’-C2’ dehydrogenation occurs at the final step of biosynthesis.アクセプト後にアブストラクト等変更あり。This work was supported by a Grants‐in‐Aid for Scientific Research on Innovative Areas from the Ministry of Education, Culture, Sports, Science and Technology of Japan (MEXT), and a Noda Institute for Scientific Research Grant.Supporting information for this articleis available on the WWW under http://dx.doi.org/10.1002/cbic.201500393

Usefulness of hexamethylenetetramine in combination with chemotherapy using free and pegylated liposomal doxorubicin in vivo, referring to the effect on quiescent cells

SCC VII tumor-bearing mice were continuously given 5-bromo-2'-deoxyuridine (BrdU) to label all intratumor proliferating (P) cells. They received hexamethylenetetramine (HMTA) either once intraperitoneally or continuously subcutaneously together with chemotherapy using intraperitoneally administered free doxorubicin (DXR) or intravenously injected pegylated liposomal doxorubicin (PLD). One hour after the free DXR loading or 24 h after the PLD loading, the response of intratumor quiescent (Q) cells was assessed in terms of the micronucleus frequency using immunofluorescence staining for BrdU. The response of the total (P + Q) tumor cell population was determined from the tumors not treated with BrdU. Encapsulation of DXR into pegylated liposomes significantly enhanced cytotoxicity, especially in Q cells. HMTA, especially when administered continuously, efficiently increased the sensitivity to DXR, particularly in Q cells. The increase in sensitivity on the continuous rather than single administration of HMTA was a little clearer in the total cell population than in Q cells. DXR's encapsulation into pegylated liposomes and combination with HMTA, particularly when administered continuously, apparently reduced the difference in sensitivity to free DXR between the total and Q cell populations. In terms of the tumor cell-killing effect as a whole, including Q cells, the encapsulation of DXR into pegylated liposomes and combination with HMTA, particularly through continuous administration, are very promising, taking into account that HMTA has been used clinically

The genome sequence of Streptomyces rochei 7434AN4, which carries a linear chromosome and three characteristic linear plasmids

Streptomyces rochei 7434AN4 produces two structurally unrelated polyketide antibiotics, lankacidin and lankamycin, and carries three linear plasmids, pSLA2-L (211 kb), -M (113 kb), and -S (18 kb), whose nucleotide sequences were previously reported. The complete nucleotide sequence of the S. rochei chromosome has now been determined using the long-read PacBio RS-II sequencing together with short-read Illumina Genome Analyzer IIx sequencing and Roche 454 pyrosequencing techniques. The assembled sequence revealed an 8,364,802-bp linear chromosome with a high G + C content of 71.7% and 7,568 protein-coding ORFs. Thus, the gross genome size of S. rochei 7434AN4 was confirmed to be 8,706,406 bp including the three linear plasmids. Consistent with our previous study, a tap-tpg gene pair, which is essential for the maintenance of a linear topology of Streptomyces genomes, was not found on the chromosome. Remarkably, the S. rochei chromosome contains seven ribosomal RNA (rrn) operons (16S-23S-5S), although Streptomyces species generally contain six rrn operons. Based on 2ndFind and antiSMASH platforms, the S. rochei chromosome harbors at least 35 secondary metabolite biosynthetic gene clusters, including those for the 28-membered polyene macrolide pentamycin and the azoxyalkene compound KA57-A.This work was supported by Grants-in-Aid for Scientific Research on Innovative Areas (23108515, 25108718 and 17H05446 to K.A.) from Ministry of Education, Culture, Sports, Science and Technology of Japan (MEXT), Grants-in-Aid for Scientific Research (B) (16H04917 to K.A.) from the Japan Society for the Promotion of Science (JSPS), and the Sasakawa Scientific Research Grant from the Japan Science Society to Y.N. This work was partly supported by a JSPS A3 Foresight Program. A.A.F. and R.M. were supported by the Indonesia Endowment Fund for Education (LPDP). Sequencing analysis using an Illumina GAIIx sequencer was supported by the Grant in Aid for Scientific Research on Innovative Areas (22108010 to J.I.) from MEXT

放線菌の線状ゲノムの構造と機能の多様性

研究期間:平成16-18年度 ; 研究種目:基盤研究A ; 課題番号:16208010原著には既発表論文の別刷を含む

Ferroelectric Switching of Vinylidene and Trifluoroethylene Copolymer Thin Films on Au Electrodes Modified with Self-Assembled Monolayers

The ferroelectric switching characteristics of a vinylidene fluoride and trifluoroethylene copolymer were significantly changed via the chemical modification of a gold electrode with an alkanethiol self-assembled monolayer (SAM). The alkanethiol SAM-Au electrode successfully suppressed the leakage current (dark current) from the electrode to the bulk ferroelectric. Smaller leakage currents led to the formation of an effective electric field in the bulk ferroelectric. At switching cycles ranging from 10 to 100 kHz, significant changes in the ferroelectric properties were observed. At 100 kHz, a remanent polarization (Pr) of 68 mC·m−2 was measured, whereas a very small Pr value of 2.4 mC·m−2 was measured for the sample without a SAM. The switching speed of the SAM-Au electrode is as twice as fast as that of the unmodified electrode. A large potential barrier was formed via the insertion of a SAM between the Au electrode and the ferroelectric, effectively changing the ferroelectric switching characteristics

Quickly Updatable Hologram Images Using Poly(N-vinyl Carbazole) (PVCz) Photorefractive Polymer Composite

material