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291.
Kawarai T Furukawa S Ogihara H Yamasaki M 《Applied and environmental microbiology》2007,73(14):4673-4676
We found that species combinations such as Lactobacillus casei subsp. rhamnosus IFO3831 and Saccharomyces cerevisiae Kyokai-10 can form a mixed-species biofilm in coculture. Moreover, the Kyokai-10 yeast strain can form a biofilm in monoculture in the presence of conditioned medium (CM) from L. casei IFO3831. The active substance(s) in bacterial CM is heat sensitive and has a molecular mass of between 3 and 5 kDa. In biofilms from cocultures or CM monocultures, yeast cells had a distinct morphology, with many hill-like protrusions on the cell surface. 相似文献
292.
Ken-Ichi Kodaira Akira Taketo 《Biochimica et Biophysica Acta (BBA) - Gene Structure and Expression》1984,783(2):171-178
Various mutants were isolated from a microvirid (isometric single-stranded DNA) phage α3, by mutagenesis with hydroxylamine or nitrous acid. They were divided into eight complementation groups, and mainly by genetic crosses the gene alignment was determined as -A-B-C′-D-J′-F-G-H-. Except for groups C′ and J′, each defective gene product was clearly discerned in electropherograms of proteins extracted from the phage-infected suppressor-negative (Su?) Escherichia coli. Only gene A mutants abolished synthesis of the progeny replicative-form DNA (RF), whereas mutants belonging to groups B, C′, D, E, F and J′ affected RF replication at late stage, as well as synthesis of the single-stranded DNA (SS). Additional properties of several mutants are also discussed. 相似文献
293.
Masataka Horiuchi Kosei Takeuchi Nobuo Noda Nobuyuki Muroya Toru Suzuki Takahisa Nakamura Junko Kawamura-Tsuzuku Kiyohiro Takahasi Tadashi Yamamoto Fuyuhiko Inagaki 《The Journal of biological chemistry》2009,284(19):13244-13255
The Tob/BTG family is a group of antiproliferative proteins containing two
highly homologous regions, Box A and Box B. These proteins all associate with
CCR4-associated factor 1 (Caf1), which belongs to the ribonuclease D (RNase D)
family of deadenylases and is a component of the CCR4-Not deadenylase complex.
Here we determined the crystal structure of the complex of the N-terminal
region of Tob and human Caf1 (hCaf1). Tob exhibited a novel fold, whereas
hCaf1 most closely resembled the catalytic domain of yeast Pop2 and human
poly(A)-specific ribonuclease. Interestingly, the association of hCaf1 was
mediated by both Box A and Box B of Tob. Cell growth assays using both
wild-type and mutant proteins revealed that deadenylase activity of Caf1 is
not critical but complex formation is crucial to cell growth inhibition. Caf1
tethers Tob to the CCR4-Not deadenylase complex, and thereby Tob gathers
several factors at its C-terminal region, such as poly(A)-binding proteins, to
exert antiproliferative activity.The Tob/BTG family (also called the APRO family) is a group of
antiproliferative proteins (1,
2) consisting of Tob
(3), Tob2
(4), BTG1
(5), BTG2/Tis21/PC3
(6-8),
PC3B (9), and ANA/BTG3
(10,
11) in mammalian cells,
in Drosophila, and FOG-3 in Caenorhabditis elegans
( AF17746412). A recent genome project
reported that the BTG/Tob family protein had already existed in
Choanoflagellida Monosiga brevicollis MX1. The N-terminal region of
the Tob/BTG family proteins is conserved and includes two highly homologous
regions, Box A and Box B. The Tob/BTG family proteins are involved in cell
cycle regulation in a variety of cells such as T lymphocytes, fibroblasts,
epithelial cells, and germ cells. In Tob-deficient mice, the incidence of
liver tumors is higher than in wild-type mice. Furthermore, because the levels
of tob expression are often repressed in human lung cancers,
suppression of its expression is thought to contribute to tumor progression
(13).The antiproliferative activities of the Tob/BTG family proteins are due to
their association with target proteins in cells. For example, Tob associates
with SMAD family proteins and acts as a negative regulator of SMAD signaling.
In osteoblasts, this negative regulation occurs via association with SMAD 1,
5, 6, and 8 (14,
15), and via association with
SMAD 2 and 4 in anergic quiescent T cells
(16). Tob/BTG family proteins
also bind to protein arginine methyltransferase, which regulates chromatin
assembly by histone methylation
(17). Much evidence has been
accumulated to suggest that CCR4-associated factor 1
(Caf1),2 also known as
Cnot7 and involved in the CCR4-Not deadenylase complex, is a common binding
partner of the Tob/BTG family proteins
(4,
18-21).
To reveal the functions of Caf1 in vivo, caf1-/- mice have
been generated in two groups. Male caf1-deficient mice are infertile
because of a malfunction of the testicular somatic cells that leads to a
defect in spermatogenesis (22,
23). Genetic analysis of the
nematode C. elegans also suggests that FOG3 (Tob orthologue)
interacts with CCF1, the C. elegans homologue of Caf1, and that this
interaction is essential for germ cells to initiate spermatogenesis
(24).Mouse and human Caf1 (mCaf1 and hCaf1) were found as homologues of yeast
Pop2, a component of the CCR4-Not complex
(18,
25). Yeast Pop2 displays weak
RNase activity but enhances the deadenylation of the poly(A) tail of mRNA by
the CCR4-Not deadenylase complex
(26-29).
The primary structure of mammalian Caf1 is related to that of the ribonuclease
D (RNase D) family, and all of the active site residues are well conserved
(30). Indeed, both mCaf1 and
hCaf1 have deadenylase activity
(31-33).Although the relationship between cell cycle repression and poly(A)
deadenylation is not well understood, mRNA degradation and synthesis are major
events in maintaining the cell cycle
(34). The mRNAs in a
eukaryotic cell have a wide range of half-lives. Degradation of mRNA is
initiated by shortening of the poly(A) tail. Thereafter, the 5′-cap
structure is removed and the remaining portion of the mRNA is rapidly
degraded. The degradation of eukaryotic mRNAs is regulated precisely at each
stage of the cell cycle. Tob was reported to associate with inducible
poly(A)-binding protein (iPABP) and to abrogate the translation of
interleukin-2 mRNA in vitro
(35). Recent reports also
showed that Tob and BTG2 interact with the CCR4-Not deadenylase complex using
the Tob/BTG2 domain and the cytoplasmic poly(A)-binding protein (PABPC1) using
the C-terminal tail and enhanced mRNA degradation
(36-38).To help elucidate the relationship between the antiproliferative activity
of Tob and the degradation of the poly(A) tail, we determined the crystal
structure of the Tob-hCaf1 complex. We found that hCaf1 has a structure
similar to yeast Pop2 and human PARN of deadenylases, exonuclease I, and the
Klenow fragment of DNA polymerase I from Escherichia coli. In
contrast, Tob has a novel structure. Specifically, Box A and Box B mediate the
interaction between Tob and hCaf1. Cell growth assays using the wild and
mutant proteins, together with the structural studies, revealed that the
complex formation is crucial to cell growth inhibition. 相似文献
294.
Yamanaka Y Heike T Kumada T Shibata M Takaoka Y Kitano A Shiraishi K Kato T Nagato M Okawa K Furushima K Nakao K Nakamura Y Taketo MM Aizawa S Nakahata T 《Mechanisms of development》2008,125(5-6):441-450
Borealin/DasraB is a member of the chromosomal passenger protein complex (CPC) required for proper segregation of chromosomes during mitosis. In Drosophila melanogaster, inactivation of Borealin/DasraB results in polyploidy, delayed mitosis and abnormal tissue development, indicating its critical role for cell proliferation. However, the in vivo role of mammalian Borealin/DasraB remains unclear. Here, we analyzed the expression of Borealin/DasraB and found that borealin is widely expressed in embryonic tissues and later restricted to adult tissues which relies on rapid cell proliferation. To determine the role of borealin during mouse development, we generated borealin-null mice through targeted disruption. While heterozygous mice developed normally, disruption of both borealin alleles resulted in early embryonic lethality by 5.5 dpc (days postcoitus) due to mitotic defects and apoptosis in blastocyst cells that showed microtubule disorganization and no CPC enrichment. At 5.5 dpc, borealin-null embryos exhibited excessive apoptosis and elevated expression of p53. However, loss of p53 did not abrogate or delay embryonic lethality, revealing that Borealin/DasraB inactivation triggered impaired mitosis and apoptosis though p53-independent mechanisms. Our data show that Borealin/DasraB is essential for cell proliferation during early embryonic development, and its early embryonic lethality cannot be rescued by the loss of p53. 相似文献
295.
Ectopic Wnt/beta-catenin signaling induces neurogenesis in the spinal cord and hindbrain floor plate
The most ventral structure of the developing neural tube, the floor plate (FP), differs in neurogenic capacity along the neuraxis. The FP is largely non-neurogenic at the hindbrain and spinal cord levels, but generates large numbers of dopamine (mDA) neurons at the midbrain levels. Wnt1, and other Wnts are expressed in the ventral midbrain, and Wnt/beta catenin signaling can at least in part account for the difference in neurogenic capacity of the FP between midbrain and hindbrain levels. To further develop the hypothesis that canonical Wnt signaling promotes mDA specification and FP neurogenesis, we have generated a model wherein beta-catenin is conditionally stabilized throughout the FP. Here, we unambiguously show by fate mapping FP cells in this mutant, that the hindbrain and spinal cord FP are rendered highly neurogenic, producing large numbers of neurons. We reveal that a neurogenic hindbrain FP results in the altered settling pattern of neighboring precerebellar neuronal clusters. Moreover, in this mutant, mDA progenitor markers are induced throughout the rostrocaudal axis of the hindbrain FP, although TH+ mDA neurons are produced only in the rostral aspect of rhombomere (r)1. This is, at least in part, due to depressed Lmx1b levels by Wnt/beta catenin signaling; indeed, when Lmx1b levels are restored in this mutant, mDA are observed not only in rostral r1, but also at more caudal axial levels in the hindbrain, but not in the spinal cord. Taken together, these data elucidate both patterning and neurogenic functions of Wnt/beta catenin signaling in the FP, and thereby add to our understanding of the molecular logic of mDA specification and neurogenesis. 相似文献
296.
A monoclonal antibody that specifically reacts with human embryonal carcinomas, spermatogonia and oocytes is able to induce human EC cell death 总被引:1,自引:0,他引:1
297.
Host functions involved in synthesis of parental replicative form of bacteriophage G4 were investigated using various replication mutants of Escheria coli. In dna+ bacteria, conversion of single-stranded viral DNA to replicative form DNA was insensitive to 200 microng/ml of rifampicin or 25 microng/ml of chloramphenicol. At high temperature, synthesis of parental replicative form was unaffected in mutants thermosensitive for dnaA, dnaB, dnaC(D), dnaE or dnaH. In dnaG or dnaZ mutants, however, parental replicative from DNA synthesis was clearly thermosensitive at 43 degrees C. Although the host rep product was essential for viral multiplication, the conversion of single stranded to replicative form was independent of the rep function. 相似文献
298.
299.
Mapping of five subtype genes for muscarinic acetylcholine receptor to mouse chromosomes. 总被引:2,自引:0,他引:2
M Matsui Y Araki H Karasawa N Matsubara M M Taketo M F Seldin 《Genes & genetic systems》1999,74(1):15-21
Muscarinic acetylcholine receptors in mammals consist of five subtypes (M1-M5) encoded by distinct genes. They are widely expressed throughout the body and play a variety of roles in the peripheral and central nervous systems. Although their pharmacological properties have been studied extensively in vitro, colocalization of the multiple subtypes in each tissue and lack of subtype-specific ligands have hampered characterization of the respective subtypes in vivo. We have mapped mouse genomic loci for all five genes (Chrm1-5) by restriction fragment length variant (RFLV) analyses in interspecific backcross mice. Chrm1, Chrm2, and Chrm3 were mapped to chromosome (Chr) 19, 6, and 13, respectively. Both Chrm4 and Chrm5 were mapped to Chr 2. Although a comparison of their map positions with other mutations in their vicinities suggested a possibility that the El2 (epilepsy 2) allele might be a mutation in Chrm5, sequencing analyses of the Chrm5 gene in the El2 mutant mice did not support such a hypothesis. 相似文献
300.
Sensitivity of Escherichia coli to viral nucleic acid. 8. Idiosyncrasy of Ca2+-dependent competence for DNA 总被引:9,自引:0,他引:9
A Taketo 《Journal of biochemistry》1974,75(4):895-904