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Streptomyces sp. strain K30 was isolated from soil next to a city high way in Münster (Germany) according to its ability to degrade natural and synthetic poly(cis-1,4-isoprene) rubber and to form clear zones on natural rubber latex agar plates. The clear zone forming phenotype was used to clone the responsible gene by phenotypic complementation of a clear zone negative mutant. An open reading frame (lcp) of 1,191 bp was identified, which was preceded by a putative signal sequence and restored the capability to form clear zones on natural rubber latex in the mutant. The putative translation product exhibited strong homologies (50% aa identity) to a putative secreted protein from Streptomyces coelicolor strain A3(2), another clear zone forming strain. Heterologous expression of lcp of Streptomyces sp. strain K30 in Streptomyces lividans strain TK23 enabled the latter to form clear zones on latex-overlay agar plates and to accumulate a degradation product of about 12 kDa containing aldehyde groups. Two ORFs putatively encoding a heterodimeric molybdenum hydroxylase (oxiAB) were identified downstream of lcp in Streptomyces sp. strain K30 strain which exerted a positive effect on clear zone formation and enabled the strain to oxidize the resulting aldehydes. Heterologous expression of a fragment harboring lcp plus oxiAB in S. lividans TK23 resulted in accumulation of aldehydes only in the presence of 10 mM tungstate. Determination of protein content during cultivation on poly(cis-1,4-isoprene) revealed an increase of the cellular protein, and gel permeation chromatography analysis indicated a shift of the molecular weight distribution of the rubber to lower values in the transgenic S. lividans strains and in the wild type, thus confirming utilization and degradation of rubber. Therefore, for the first time, genes responsible for clear zone formation on natural rubber latex and synthetic cis-1,4-polyisoprene degradation in Gram-positive bacteria were identified and characterized.

The gene queD encoding quercetinase of Streptomyces sp. FLA, a soil isolate related to S. eurythermus (T), was identified. Quercetinases catalyze the 2,4-dioxygenolytic cleavage of 3,5,7,3',4'-pentahydroxyflavone to 2-protocatechuoylphloroglucinol carboxylic acid and carbon monoxide. The queD gene was expressed in S. lividans and E. coli, and the recombinant hexahistidine-tagged protein (QueDHis(6)) was purified. Several flavonols were converted by QueDHis(6), whereas CO formation from the 2,3-dihydroflavonol taxifolin and the flavone luteolin were not observed. In contrast to bicupin quercetinases from Aspergillus japonicus and Bacillus subtilis, and bicupin pirins showing quercetinase activity, QueD of strain FLA is a monocupin exhibiting 35.9% sequence identity to the C-terminal domain of B. subtilis quercetinase. Its native molecular mass of 63 kDa suggests a multimeric protein. A queD-specific probe hybridized with fragments of genomic DNA of four other quercetin degrading Streptomyces strains, but not with DNA of B. subtilis. Potential ORFs upstream of queD probably code for a serine protease and an endoribonuclease; two ORFs downstream of queD may encode an amidohydrolase and a carboxylesterase. This arrangement suggests that queD is not part of a catabolic gene cluster. Quercetinases might play a major role as detoxifying rather than catabolic enzymes.

About 22,000 1-methyl-3-nitro-1-nitrosoguanidine-and UV-induced mutants of the rubber-degrading bacterium Streptomyces sp. strain K30 were characterized for the ability to produce clear zones on natural rubber latex overlay agar plates. Thirty-five mutants were defective solely in cleavage of rubber and were phenotypically complemented with the wild-type lcp (latex clearing protein) gene. Sixty-nine mutants exhibited a pleiotropic phenotype and were impaired in utilization of rubber and xylan, indicating that the enzymes responsible for the initial cleavage of these polymers are exported by the same secretion pathway (Q. In contrast, oxiB and oxiA, which are located directly downstream of lcp and putatively encode a heteromultimeric aldehyde dehydrogenase oxidizing the primary cleavage products generated by Lcp from poly(cis-1,4-isoprene), were expressed only in the presence of poly(cis-1,4-isoprene). Expression of lcp at a low level is thus required for sensing the polymer in the medium. Rubber degradation products may then induce the transcription of genes coding for enzymes catalyzing the later steps of poly(cis-1,4-isoprene) degradation and the transcription of lcp itself. lcp, oxiB, and oxiA seem to constitute an operon, as a polycistronic mRNA comprising these three genes was detected. The transcriptional start site of lcp was mapped 400 bp upstream of the lcp start codon.KThe microbial degradation of natural and synthetic poly(cis-1,4-isoprene) rubber is currently being intensively investigated (for a review, see reference 24), and two different strategies for degradation of isoprene rubber have been described (18). Members of one group of organisms form clear zones on natural rubber latex agar plates and generally belong to the mycelium-forming actinomycetes, such as Actinoplanes, Streptomyces, and Micromonospora. Members of the second group comprise nocardioform actinomycetes like Gordonia, Mycobacterium, and Nocardia and do not produce translucent halos; instead, they require direct contact with the rubber substrates (37). Xanthomonas sp. strain 35Y is the only known rubberdegrading bacterium that does not belong to the actinomycetes but is a gram-negative bacterium (34); however, in terms of its strategy for rubber degradation, it belongs to the first group and forms halos on rubber-containing agar plates.Whereas no proteins involved in rubber degradation in the nocardioform actinomycetes are known so far, the rubbercleaving dioxygenase RoxA occurring in culture supernatants of Xanthomonas sp. strain 35Y (16, 34) and the lcp gene encoding Lcp (latex clearing protein) in Streptomyces sp. strain K30 have recently been identified and characterized by Braaz et al. (6) and Rose and Steinbüchel (27), respectively. Both of these bacteria belong to the so-called clear-zone-forming group of rubber-degrading bacteria, and obviously, both RoxA and Lcp are secreted into the extracellular medium, leading to the formation of translucent halos on natural rubber latex. Sequence analysis of Lcp and characterization...

A long-chain derivative of 1,3-dioxolane sodium propyloxy sulfate, with similar denaturing and electrophoretic properties as SDS, and facilitated protein identification following polyacrylamide gel electrophoresis (PAGE) for Coomassie-stained protein bands, has been tested. Comparative acid-labile surfactant/sodium dodecyl sulfate two-dimensional (ALS/SDS 2-D)-PAGE experiments of lower abundant proteins from the proteomes of regenerating rat retina and mouse brain show that peptide recovery for mass spectrometry (MS) mapping is significantly enhanced using ALS leading to more successful database searches. ALS may influence some procedures in proteomic analysis such as the determination of protein content and methods need to be adjusted to that effect. The promising results of the use of ALS in bioanalytics call for detailed physicochemical investigations of surfactant properties.

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Fibroblast growth factor 2 (FGF2), an intensively studied heparin-binding cytokine, is an important modulator of cell growth and differentiation under both physiological and pathophysiological conditions. It has been shown recently that ATP binds to FGF2 and that this binding is crucial for its biological function. In this study we demonstrated that divalent cations were not necessary for binding of ATP to FGF2, but it could be demonstrated that heparin blocked the labelling of FGF2 with ATP indicating an involvement of the heparin-binding domain (aa 128-144) in ATP-binding. FGF2, bound to Heparin Sepharose, could be eluted with ATP and GTP, but not with cAMP, AMP or ADP. Successive mutation of positively charged amino acid residues located in the heparin-binding domain drastically reduced the signal intensity of [gamma-(32)P]ATP labelled FGF2 indicating that this domain is not only important for heparin binding to FGF2 but also for ATP-binding.

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