Sixty-eight Actinoplanes isolates from freshwater sediments were compared through 89 unit characters with marker strains of the genera Actinoplanes, Ampullariella, Dactylosporangium, Micromonospora, Planobispora, Spirillospora and Streptosprangium. The data were examined using the simple matching, Jaccard and pattern coefficients and clustering was achieved using the unweighted pair group method with arithmetic averages algorithm. The numerical classification was only marginally affected by the statistics used or by test error, estimated at 5%. Most of the environmental isolates were recovered in five major clusters that were equated with taxospecies. Seven major, nine minor and 29 single-member clusters defined by the SSM coefficient at the 83% similarity (S-) level, were assigned to two aggregate groups circumscribed at the 68% S-level. The first cluster group was composed of strains belonging to the genera Actinoplanes (including Ampullariella), Dactylosporangium and Micromonospora and the second included representatives of the genera Planobispora, Planomonospora, Spirillospora and Streptosporangium. Selected Actinoplanes strains subjected to chemical analyses contained complex mixtures of straight-and branched-chain fatty acids, tetrahydrogenated menaquinones with nine isoprene units as the predominant isoprenologue, and major amounts of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol and phosphatidylinositol; the representative environmental isolates were also shown to contain meso-and hydroxydiaminopimelic acid; the principal wall sugars were arabinose, galactose, glucose, mannose and xylose. The chemical and numerical taxonomic data support the integrity of established species of Actinoplanes, with the exception of Actinoplanes caeruleus, and show that the five major clusters encompassing environmental isolates merit the rank of species. It is proposed that the five novel taxa be assigned to the genus Actinoplanes as Actinoplanes consettensis sp. nov., Actinoplanes derwentensis sp. nov., Actinoplanes durhamensis sp. nov., Actinoplanes humidus sp. nov., and Actinoplanes palleronii sp. nov. Similarly, the genera Actinoplanes, Dactylosporangium, Micromonospora and Pilimelia have many properties in common and it is proposed that they be classified in the family Micromonosporaceae Krassilnikov 1938; an emended description of this taxon is given. The family Streptosporangiaceae fam. nov. is proposed to accommodate organisms assigned to the genera Microbispora, Microtetraspora, Planobispora, Planomonospora and Streptosporangium.

Parasitic protists belonging to the genus Leishmania synthesize the non-canonical carbohydrate reserve, mannogen, which is composed of b-1,2-mannan oligosaccharides. Here, we identify a class of dualactivity mannosyltransferase/phosphorylases (MTPs) that catalyze both the sugar nucleotide-dependent biosynthesis and phosphorolytic turnover of mannogen. Structural and phylogenic analysis shows that while the MTPs are structurally related to bacterial mannan phosphorylases, they constitute a distinct family of glycosyltransferases (GT108) that have likely been acquired by horizontal gene transfer from gram-positive bacteria. The seven MTPs catalyze the constitutive synthesis and turnover of mannogen. This metabolic rheostat protects obligate intracellular parasite stages from nutrient excess, and is essential for thermotolerance and parasite infectivity in the mammalian host. Our results suggest that the acquisition and expansion of the MTP family in Leishmania increased the metabolic flexibility of these protists and contributed to their capacity to colonize new host niches.

The interaction between fungal endopolygalacturonases (EPGs) and polygalacturonase-inhibiting proteins (PGIPs) found in plant cell walls has been well established. The typical EPG/PGIP interaction is characterized by high affinity, reversibility, and a 1:1 stoichiometry that results in lowering the catalytic rate of a particular endopolygalacturonase by up to 99.7%. Various EPG and PGIP isoforms and glycoforms have been isolated and characterized, and combinations of EPGs and PGIPs demonstrate a range of enzyme inhibition. EPG/PGIP interactions have prompted many researchers to suspect the involvement of these proteins in the production of specific signals (oligosaccharins) during plant pathogenesis. We have recently reported on initial studies in our laboratory indicating that, for certain EPG/PGIP combinations, the specific activity of EPG is increased beyond that characteristic of the enzyme alone. In this paper, we present a detailed analysis of the product of the interaction of native Phaseolus vulgaris PGIP-2 with five EPGs from Aspergillus niger, namely PGI, PGII, PGA, PGB, and PGC in the presence of homogalacturonan. We demonstrate that for PGA and PGC, the interaction with PGIP-2 may result in either inhibition or activation in a manner that is pH dependent. This data suggests the need for a reevaluation of the conventional description applied to PGIPs; suggestions include polygalacturonase-binding protein and polygalacturonase-modulating protein.

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