Integration and mapping of Bacillus megaterium genes which code for small, acid-soluble spore proteins and their protease.

Four genes (ssp genes) coding for small, acid-soluble spore proteins of Bacillus megaterium and the gene for the protease that cleaves them during germination were cloned in the integratable plasmid pJH101. Each plasmid was integrated into the B. megaterium chromosome by a Campbell-type mechanism, allowing mapping of all five genes. The gene for the small, acid-soluble spore protein-specific protease (gpr) mapped near rib, and the sspA gene mapped between argA and hisA. The three other genes of the spp gene family (sspB, -D, and -F) all mapped near metC/D, with the order: sspF-sspD-metC/D-hemA-argO-sspB. While neither gpr nor sspF has been mapped in B. subtilis, the positions of the sspA, -B, and -D loci are similar in B. megaterium and B. subtilis, suggesting that the members of this multigene family have not recently undergone significant movement on the chromosome. It appears that more gene rearrangement has occurred in the flanking genes than has occurred in the ssp family of genes producing the small, acid-soluble spore proteins.     

Purification and Properties of Lectins from a Mushroom,Pleurotus cornucopiae

Hemagglutinating activity in fruit bodies of Pleurotus cornucopiae was separated by DEAE column chromatography into two, adsorbed and unadsorbed, fractions. From the unadsorbed fraction, three active substances were purified and characterized. The main component (PCL-a) consisted of two identical subunits with an apparent molecular mass of 16kDa and the second (PCL-b) consisted of two heterogeneous subunits of 16 and 15 kDa. The three lectins as well as the two kinds of subunits were immunologically cross-reactive with anti-PCL-a serum. Amino acid compositions of the two subunits were similar, and N-terminal residues of the subunits were blocked. Hemagglutinating activities of the three lectins were not inhibited by any monosaccharide tested but were strongly inhibited by asialo-mucin. From these results, the three lectins in P. cornucopiae were found to be isolectins.     

Proteins that interact with GTP in Streptomyces griseus and its possible implication in morphogenesis

Abstract By cross-linking with [α-³²P]GTP or [γ-³²P]GTP with or without UV treatment, several proteins of Streptomyces griseus were shown to interact with GTP in specific ways. After gel electrophoresis, 19 bands of radioactivity were found; 12 bands were assigned as GTP-binding proteins and 6 bands as phosphorylated proteins. One band was assumed to be a guanylylated protein. The profile of radioactive bands was similar between cells prepared from liquid or solid culture, but markedly different between growth phases. A mutant (strain M-1) defective in aerial mycelium formation, which was originally found as a decoyinine-resistant isolate, was found to have a different profile of phosphorylated proteins.     

N-terminal amino acid residues mediate protein-protein interactions between DNA-bound alpha /beta -type small, acid-soluble spore proteins from Bacillus species

The binding of alpha/beta-type small, acid-soluble spore proteins (SASP) to DNA of spores of Bacillus species is the major determinant of DNA resistance to a variety of damaging treatments. The primary sequence of alpha/beta-type SASP is highly conserved; however, the N-terminal third of these proteins is less well conserved than the C-terminal two-thirds. To determine the functional importance of residues in the N-terminal region of alpha/beta-type SASP, variants of SspC (a minor alpha/beta-type SASP from Bacillus subtilis) with modified N termini were generated and their structural and DNA binding properties studied in vitro and in vivo. SspC variants with deletions of up to 14 residues ( approximately 20% of SspC residues) were able to bind DNA in vitro and adopted similar conformations when bound to DNA, as determined by circular dichroism spectroscopy and protein-protein cross-linking. Progressive deletion of up to 11 N-terminal residues resulted in proteins with progressively lower DNA binding affinity. However, SspC(Delta)(14) (in which 14 N-terminal residues have been deleted) showed significantly higher affinity for DNA than the larger proteins, SspC(Delta)(10) and SspC(Delta)(11). The affinity of these proteins for DNA was shown to be largely dependent upon the charge of the first few N-terminal residues. These results are interpreted in the context of a model for DNA-dependent alpha/beta-type SASP protein-protein interaction involving the N-terminal regions of these proteins.     

Analysis of deamidation of small, acid-soluble spore proteins from Bacillus subtilis in vitro and in vivo.

Deamidation of one specific asparagine residue in an alpha/beta-type small, acid-soluble spore protein (SASP) of Bacillus subtilis took place readily in vitro (time for 50% deamidation [t(1/2)], approximately 1 h at 70 degrees C), and the deamidated SASP no longer bound to DNA effectively. However, DNA binding protected against this deamidation in vitro. A mutant alpha/beta-type SASP in which the reactive asparagine was changed to aspartate also failed to bind to DNA in vitro, and this protein did not restore UV radiation and heat resistance to spores lacking the majority of their alpha/beta-type SASP. When expressed in Escherichia coli, where it is bound to DNA, the alpha/beta-type SASP deamidated with a t(1/2) of 2 to 3 h at 95 degrees C. However, the alpha/beta-type SASP was extremely resistant to deamidation within spores (t(1/2), >50 h at 95 degrees C). A gamma-type SASP of B. subtilis also deamidated readily in vitro (t(1/2) for one net deamidation, approximately 1 h at 70 degrees C), but this protein (which is not associated with DNA) deamidated fairly readily in spores (t(1/2), approximately 1 h at 95 degrees C). Total spore core protein also deamidated in vivo, although the rate was two- to threefold slower than that of deamidation of total protein in heated vegetative cells. These data indicate that protein deamidation is slowed significantly in spores, presumably due to the spore's environment. However, alpha/beta-type SASP are even more strongly protected against deamidation in vivo, presumably by their binding to spore DNA. Thus, not only do alpha/beta-type SASP protect spore DNA from damage; DNA also protects alpha/beta-type SASP.     

Identification of stsC, the gene encoding the l-glutamine:scyllo-inosose aminotransferase from streptomycin-producing Streptomycetes

Eight new genes, strO-stsABCDEFG, were identified by sequencing DNA in the gene cluster that encodes proteins for streptomycin production of Streptomyces griseus N2-3-11. The StsA (calculated molecular mass 43.5 kDa) and StsC (45.5 kDa) proteins – together with another gene product, StrS (39.8 kDa), encoded in another operon of the same gene cluster – show significant sequence identity and are members of a new class of pyridoxal-phosphate-dependent aminotransferases that have been observed mainly in the biosynthetic pathways for secondary metabolites. The aminotransferase activity was demonstrated for the first time by identification of the overproduced and purified StsC protein as the l-glutamine:scyllo-inosose aminotransferase, which catalyzes the first amino transfer in the biosynthesis of the streptidine subunit of streptomycin. The stsC and stsA genes each hybridized specifically to distinct fragments in the genomic DNA of most actinomycetes tested that produce diaminocyclitolaminoglycosides. In contrast, only stsC, but not stsA, hybridized to the DNA of Streptomyces hygroscopicus ssp. glebosus, which produces the monoaminocyclitol antibiotic bluensomycin; this suggests that both genes are specifically used in the first and second steps of the cyclitol transamination reactions. Sequence comparison studies performed with the deduced polypeptides of the genes adjacent to stsC suggest that the enzymes encoded by some of these genes [strO (putative phosphatase gene), stsB (putative oxidoreductase gene), and stsE (putative phosphotransferase gene)] also could be involved in (di-)aminocyclitol synthesis. Received: 7 January 1997 / Accepted: 24 March 1997     

Cloning and nucleotide sequencing of genes for small, acid-soluble spore proteins of Bacillus cereus, Bacillus stearothermophilus, and "Thermoactinomyces thalpophilus"

As found previously with other Bacillus species, spores of B. stearothermophilus and "Thermoactinomyces thalpophilus" contained significant levels of small, acid-soluble spore proteins (SASP) which were rapidly degraded during spore germination and which reacted with antibodies raised against B. megaterium SASP. Genes coding for a B. stearothermophilus and a "T. thalpophilus" SASP as well as for two B. cereus SASP were cloned, their nucleotide sequences were determined, and the amino acid sequences of the SASP coded for were compared. Strikingly, all of the amino acid residues previously found to be conserved in this group of SASP both within and between two other Bacillus species (B. megaterium and B. subtilis) were also conserved in the SASP coded for by the B. cereus genes as well as those coded for by the genes from the more distantly related organisms B. stearothermophilus and "T. thalpophilus." This finding strongly suggests that there is significant selective pressure to conserve SASP primary sequence and thus that these proteins serve some function other than simply amino acid storage.     

Properties of Bacillus subtilis small, acid-soluble spore proteins with changes in the sequence recognized by their specific protease.

Alpha/beta-type small, acid-soluble proteins (SASP) of dormant spores of Bacillus subtilis bind to DNA and increase its resistance to a variety of damaging agents both in vivo and in vitro. When spores germinate, degradation of alpha/beta-type SASP is rapidly initiated by a sequence-specific protease, which is termed GPR. Three mutations have been introduced into the B. subtilis sspC gene, which codes for the wild-type alpha/beta-type SASP SspCwt; all three mutations change residues in the highly conserved sequence recognized by GPR. In one mutant protein (SspCV), residue 33 (Ser) was changed to Val; in the second (SspCDL), residues 30 and 31 (Glu and Ile) were changed to Asp and Leu, respectively; and in the third mutant protein (SspCDLV), residues 30, 31, and 33 were changed to Asp, Leu, and Val. All three mutant proteins were rapidly degraded by GPR during spore germination, and SspCDL and SspCDLV were degraded by GPR in vitro at rates 8 to 9% of that for SspCwt, although not exclusively at the single site cleaved by GPR in SspCwt. These results indicate (i) that the sequence specificity of GPR is broader than originally imagined and (ii) that GPR can cleave the sequence in SspCDLV. Since the latter sequence is identical to that cleaved during the proteolytic activation of GPR, this result further supports an autoprocessing model for GPR activation during sporulation. The properties of these mutant proteins were also examined, both in vivo in B. subtilis spores and in Escherichia coli and in vitro with purified protein. SspC(v) interacted with DNA similarly to SspC(wt) in vivo, resorting UV and heat resistance to spores lacking major alpha/beta-type SASP to the same extent as SspC(wt). In contrasst, SspC(DL) had much less effect on DNA properties in vivo and bound strongly only to poly(dG) . poly(dC) in vitro; SspC(DLV) exhibited only weak binding to poly(dG).poly(dC) in vitro. These results confirm the importance of the conserved primary sequence of alpha/beta-type SASP in the binding of these proteins to spore DNA and alteration of DNA properties and show further that the GRP recognition region in alpha/beta-type SASP plays some role in DNA binding.     

Effects of mutant small, acid-soluble spore proteins from Bacillus subtilis on DNA in vivo and in vitro.

alpha/beta-type small, acid-soluble spore proteins (SASP) of Bacillus subtilis bind to DNA and alter its conformation, topology, and photochemistry, and thereby spore resistance to UV light. Three mutations have been introduced into the B. subtilis sspC gene, which codes for the alpha/beta-type wild-type SASP, SspCwt. One mutation (SspCTyr) was a conservative change, as residue 29 (Leu) was changed to Tyr, an amino acid found at this position in other alpha/beta-type SASP. The other mutations changed residues conserved in all alpha/beta-type SASP. In one (SspCAla), residue 52 (Gly) was changed to Ala; in the second (SspCGln), residue 57 (Lys) was changed to Gln. The effects of the wild-type and mutant SspC on DNA properties were examined in vivo in B. subtilis spores and Escherichia coli as well as in vitro with use of purified protein. Both SspCwt and SspCTyr interacted similarly with DNA in vivo and in vitro, restoring much UV resistance to spores lacking major alpha/beta-type SASP, causing a large increase in plasmid negative supercoiling, and altering DNA UV photochemistry from cell type to spore type. In contrast, SspCAla had no detectable effect on DNA properties in vivo or in vitro, while SspCGln had effects intermediate between those of SspCAla and SspCwt. Strikingly, neither SspCAla nor SspCGln bound well to DNA in vitro. These results confirm the importance of the conserved primary sequence of alpha/beta-type SASP in the ability of these proteins to bind to spore DNA and cause spore UV resistance.     

Determination of the chromosomal locations of four Bacillus subtilis genes which code for a family of small, acid-soluble spore proteins.

The chromosomal locations of four genes which code for small, acid-soluble spore proteins (SASP) in Bacillus subtilis have been determined. Although these four genes code for extremely homologous small, acid-soluble spore proteins (greater than 65% sequence identity), the genes are not clustered but are located at 70 degrees (adjacent to glyB [sspB gene]), 115 degrees (between metC and pyr cluster [sspD gene]), 180 degrees (between metB and kauA [sspC gene]), and 260 degrees (between ilvC and aroG [sspA gene]) on the B. subtilis genetic map.     

Purification and amino acid sequence of two small, acid-soluble proteins from Clostridium bifermentans spores

Clostridium bifermentans spores contain two major small, acid-soluble, proteins (SASP) termed SASP-alpha and beta. The amino acid sequences of SASP-alpha and beta are almost identical, and are very similar to those of alpha/beta-type SASP from spores of C. perfringens and various Bacillus species. However, the C. bifermentans proteins contain an extra five amino acids in the middle of their sequence. Surprisingly, no gamma-type SASP were found in C. bifermentans or C. perfringens spores, although these are the most prominent SASP in spores of Bacillus species.     

灰色链霉菌中乙酰木聚糖酯酶基因的克隆、表达及酶学性质研究

根据Gen Bank数据库中已报道的灰色链霉菌(Streptomyces griseus)全基因组序列,分析得到假定的乙酰木聚糖酯酶基因序列并设计引物;利用分子克隆的方法得到该菌株基因组中乙酰木聚糖酯酶基因,并构建原核表达载体p ET28a-Sgraxe,经IPTG诱导表达重组Sgr Axe,Ni-NTA亲和层析法纯化该蛋白。结果显示,克隆得到乙酰木聚糖酯酶基因axe,其序列全长1 008 bp,编码336个氨基酸。SDS-PAGE检测带有p ET28a-Sgraxe转化菌株诱导表达产物相对分子量约为37 k D,与理论值相符。纯化的重组Sgr Axe酶学性质表明,该酶最适反应温度为50℃,最适p H8.0,热稳定性较强,p H作用范围广;金属离子对酶均表现为抑制作用,尤其是Zn2+严重抑制酶活力;重组酶特征的分析揭示了其在工业中潜在的应用价值。     

Immunoelectron microscopic localization of small, acid-soluble spore proteins in sporulating cells of Bacillus subtilis.

Small, acid-soluble spore proteins SASP-alpha, SASP-beta, and SASP-gamma as well as a SASP-beta-lacZ gene fusion product were found only within the forespore compartment of sporulating Bacillus subtilis cells by using immunoelectron microscopy. The alpha/beta-type SASP were associated almost exclusively with the forespore nucleoid, while SASP-gamma was somewhat excluded from the nucleoid. These different locations of alpha/beta-type and gamma-type small, acid-soluble spore proteins within the forespore are consistent with the different roles for these two types of proteins in spore resistance to UV light.