An Assessment of the Ability of Submicron- and Micron-Size Silicone Oil Droplets in Dropped Prefillable Syringes to Invoke Early- and Late-Stage Immune Responses.

A number of biopharmaceuticals are available as lyophilized formulations along with a prefilled syringe (PFS) containing water for injection (WFI). Submicron- and micron-size droplets of lubricating silicone oil (SO) applied to the inner surface of the PFS barrel might migrate into the WFI, to which protein pharmaceuticals can adsorb, potentially inducing an immune response. In the present study, we subjected siliconized cyclo-olefin polymer PFSs filled with WFI to dropping stress to simulate actual shipping conditions as well as evaluated the risk associated with the released SO droplets. The results confirmed the undesirable effects of SO on therapeutic proteins, including adsorption to SO droplets and increased secretion of several innate cytokines from human peripheral blood mononuclear cells of a small donor panel. Assessment of immunogenicity in vivo using BALB/c mice revealed a slight increase in the plasma concentrations of antidrug antibodies over 21 days in response to SO-containing antibody samples compared to the absence of SO. These results indicate that SO droplets form complexes with pharmaceutical proteins that can potentially invoke early- and late-stage immune responses. Therefore, the use of SO-free cyclo-olefin polymer PFSs as primary containers for WFI could contribute to the enhanced safety of reconstituted biopharmaceuticals.

Mutations responsible for alcohol tolerance in the mutant of Synechococcus elongatus PCC 7942 (SY1043) obtained by single-cell screening system.

The production of alcohols directly from carbon dioxide by engineered cyanobacteria is an attractive technology for a sustainable future. Enhanced tolerance to the produced alcohols would be a desirable feature of the engineered cyanobacterial strains with higher alcohol productivity. We have recently obtained the mutant strains of Synechococcus elongatus PCC 7942 with higher tolerance to isopropanol using a single-cell screening system (Arai et al., Biotechnol. Bioeng., 114, 1771-1778, 2017). Among the mutant strains, SY1043 showed the highest isopropanol tolerance. Interestingly, SY1043 also showed higher tolerance to other alcohols such as ethanol and 1-butanol, however, the mechanisms involved in enhancing this alcohol tolerance were unclear. To reveal the alcohol tolerance mechanism of SY1043, we investigated the relationship between alcohol tolerance and four mutations found in SY1043 by genome resequencing analysis. Isopropanol tolerance was enhanced by amino acid substitution (Leu285Pro) in a hypothetical protein encoded by Synpcc7942_0180 of the wild type strain TA1297. TA4135, into which this mutation was introduced, showed a same tendency of tolerance to other alcohols (ethanol and 1-butanol).

Alcohol-tolerant mutants of cyanobacterium Synechococcus elongatus PCC 7942 obtained by single-cell mutant screening system.

Enhancement of alcohol tolerance in microorganisms is an important strategy for improving bioalcohol productivity. Although cyanobacteria can be used as a promising biocatalyst to produce various alcohols directly from CO2 , low productivity, and low tolerance against alcohols are the main issues to be resolved. Nevertheless, to date, a mutant with increasing alcohol tolerance has rarely been reported. In this study, we attempted to select isopropanol (IPA)-tolerant mutants of Synechococcus elongatus PCC 7942 using UV-C-induced random mutagenesis, followed by enrichment of the tolerant candidates in medium containing 10 g/L IPA and screening of the cells with a high growth rate in the single cell culture system in liquid medium containing 10 g/L IPA. We successfully acquired the most tolerant strain, SY1043, which maintains the ability to grow in medium containing 30 g/L IPA. The photosynthetic oxygen-evolving activities of SY1043 were almost same in cells after 72 h incubation under light with or without 10 g/L IPA, while the activity of the wild-type was remarkably decreased after the incubation with IPA. SY1043 also showed higher tolerance to ethanol, 1-butanol, isobutanol, and 1-pentanol than the wild type. These results suggest that SY1043 would be a promising candidate to improve alcohol production using cyanobacteria. Biotechnol. Bioeng. 2017;114: 1771-1778. © 2017 Wiley Periodicals, Inc.

The MRX Complex Ensures NHEJ Fidelity through Multiple Pathways Including Xrs2-FHA-Dependent Tel1 Activation.

Because DNA double-strand breaks (DSBs) are one of the most cytotoxic DNA lesions and often cause genomic instability, precise repair of DSBs is vital for the maintenance of genomic stability. Xrs2/Nbs1 is a multi-functional regulatory subunit of the Mre11-Rad50-Xrs2/Nbs1 (MRX/N) complex, and its function is critical for the primary step of DSB repair, whether by homologous recombination (HR) or non-homologous end joining. In human NBS1, mutations result truncation of the N-terminus region, which contains a forkhead-associated (FHA) domain, cause Nijmegen breakage syndrome. Here we show that the Xrs2 FHA domain of budding yeast is required both to suppress the imprecise repair of DSBs and to promote the robust activation of Tel1 in the DNA damage response pathway. The role of the Xrs2 FHA domain in Tel1 activation was independent of the Tel1-binding activity of the Xrs2 C terminus, which mediates Tel1 recruitment to DSB ends. Both the Xrs2 FHA domain and Tel1 were required for the timely removal of the Ku complex from DSB ends, which correlates with a reduced frequency of imprecise end-joining. Thus, the Xrs2 FHA domain and Tel1 kinase work in a coordinated manner to maintain DSB repair fidelity.

DNA damage response clamp 9-1-1 promotes assembly of ZMM proteins for formation of crossovers and synaptonemal complex.

Formation of crossovers between homologous chromosomes during meiosis is positively regulated by the ZMM proteins (also known as SIC proteins). DNA damage checkpoint proteins also promote efficient formation of interhomolog crossovers. Here, we examined, in budding yeast, the meiotic role of the heterotrimeric DNA damage response clamp composed of Rad17, Ddc1 and Mec3 (known as '9-1-1' in other organisms) and a component of the clamp loader, Rad24 (known as Rad17 in other organisms). Cytological analysis indicated that the 9-1-1 clamp and its loader are not required for the chromosomal loading of RecA homologs Rad51 or Dmc1, but are necessary for the efficient loading of ZMM proteins. Interestingly, the loading of ZMM proteins onto meiotic chromosomes was independent of the checkpoint kinase Mec1 (the homolog of ATR) as well as Rad51. Furthermore, the ZMM member Zip3 (also known as Cst9) bound to the 9-1-1 complex in a cell-free system. These data suggest that, in addition to promoting interhomolog bias mediated by Rad51-Dmc1, the 9-1-1 clamp promotes crossover formation through a specific role in the assembly of ZMM proteins. Thus, the 9-1-1 complex functions to promote two crucial meiotic recombination processes, the regulation of interhomolog recombination and crossover formation mediated by ZMM.

RBMX: a regulator for maintenance and centromeric protection of sister chromatid cohesion.

Cohesion is essential for the identification of sister chromatids and for the biorientation of chromosomes until their segregation. Here, we have demonstrated that an RNA-binding motif protein encoded on the X chromosome (RBMX) plays an essential role in chromosome morphogenesis through its association with chromatin, but not with RNA. Depletion of RBMX by RNA interference (RNAi) causes the loss of cohesin from the centromeric regions before anaphase, resulting in premature chromatid separation accompanied by delocalization of the shugoshin complex and outer kinetochore proteins. Cohesion defects caused by RBMX depletion can be detected as early as the G2 phase. Moreover, RBMX associates with the cohesin subunits, Scc1 and Smc3, and with the cohesion regulator, Wapl. RBMX is required for cohesion only in the presence of Wapl, suggesting that RBMX is an inhibitor of Wapl. We propose that RBMX is a cohesion regulator that maintains the proper cohesion of sister chromatids.

The middle region of an HP1-binding protein, HP1-BP74, associates with linker DNA at the entry/exit site of nucleosomal DNA.

In higher eukaryotic cells, DNA molecules are present as chromatin fibers, complexes of DNA with various types of proteins; chromatin fibers are highly condensed in metaphase chromosomes during mitosis. Although the formation of the metaphase chromosome structure is essential for the equal segregation of replicated chromosomal DNA into the daughter cells, the mechanism involved in the organization of metaphase chromosomes is poorly understood. To identify proteins involved in the formation and/or maintenance of metaphase chromosomes, we examined proteins that dissociated from isolated human metaphase chromosomes by 0.4 m NaCl treatment; this treatment led to significant chromosome decondensation, but the structure retained the core histones. One of the proteins identified, HP1-BP74 (heterochromatin protein 1-binding protein 74), composed of 553 amino acid residues, was further characterized. HP1-BP74 middle region (BP74Md), composed of 178 amino acid residues (Lys(97)-Lys(274)), formed a chromatosome-like structure with reconstituted mononucleosomes and protected the linker DNA from micrococcal nuclease digestion by approximately 25 bp. The solution structure determined by NMR revealed that the globular domain (Met(153)-Thr(237)) located within BP74Md possesses a structure similar to that of the globular domain of linker histones, which underlies its nucleosome binding properties. Moreover, we confirmed that BP74Md and full-length HP1-BP74 directly binds to HP1 (heterochromatin protein 1) and identified the exact sites responsible for this interaction. Thus, we discovered that HP1-BP74 directly binds to HP1, and its middle region associates with linker DNA at the entry/exit site of nucleosomal DNA in vitro.

Simplified method for recombinant linker histone H1 purification.

We report a simplified alternative protocol for purification of recombinant linker histone H1 under non-denaturing conditions. This method takes advantage of the strong affinity of H1 to DNA and comprises nucleoprotein complex extraction from the lysate of bacterial cells overexpressing the protein, followed by two ion-exchange purification steps. The purity of the protein was at least 95%; the purified H1 was tested for nucleosome binding and was successfully fluorescently labeled for further studies.

Proteome analysis of human metaphase chromosomes.

DNA is packaged as chromatin in the interphase nucleus. During mitosis, chromatin fibers are highly condensed to form metaphase chromosomes, which ensure equal segregation of replicated chromosomal DNA into the daughter cells. Despite >1 century of research on metaphase chromosomes, information regarding the higher order structure of metaphase chromosomes is limited, and it is still not clear which proteins are involved in further folding of the chromatin fiber into metaphase chromosomes. To obtain a global view of the chromosomal proteins, we performed proteome analyses on three types of isolated human metaphase chromosomes. We first show the results from comparative proteome analyses of two types of isolated human metaphase chromosomes that have been frequently used in biochemical and morphological analyses. 209 proteins were quantitatively identified and classified into six groups on the basis of their known interphase localization. Furthermore, a list of 107 proteins was obtained from the proteome analyses of highly purified metaphase chromosomes, the majority of which are essential for chromosome structure and function. Based on the information obtained on these proteins and on their localizations during mitosis as assessed by immunostaining, we present a four-layer model of metaphase chromosomes. According to this model, the chromosomal proteins have been newly classified into each of four groups: chromosome coating proteins, chromosome peripheral proteins, chromosome structural proteins, and chromosome fibrous proteins. This analysis represents the first compositional view of human metaphase chromosomes and provides a protein framework for future research on this topic.