Bacillomycin Lc, a newantifungal antibiotic of the iturin class, was isolated from a strain of Bacillus subtilis as a set of five congeners. The structure as determined by chemical and spectrometric analyses has been shown to differ from that of bacillomycin L by sequence changes from aspartate-1 to asparagine-1 and from glutamine-5 to glutamate-5. The five congeners differ from each other only in the structure of the aliphatic side chain of the constituent /?-amino acid. The hydrophobicity of the /?-amino acid affects the antifungal activity of the congener, as activity increased in the order of increased congener retention on a reversed-phase HPLCcolumn.Iturins are antifungal antibiotics produced by Bacillus subtilis that are characterized by a cyclic peptidolipid structure consisting of eight amino acids. Their common structure consists of a macrocycle of seven a-amino acids in a LDDLLDL configuration sequence, closed by a /?-amino acid linkage. 1}During a screening of tree xylem for microorganisms with biological control potential against tree phytopathogens, several Bacillus species were isolated displaying in vitro activity against Ophiostoma ulmi (Buisman) Nannf., the Dutch elm disease fungus.2) Amongthese, Bacillus subtilis isolate FS94-14 showed the greatest activity, prompting this study to characterize the antifungal compoundsproduced by this organism.

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Erythrocyte protein 4.1 has been hypothesized to link the spectrin-actin junctional complex directly to the cytoplasmic domain of glycophorin C, but this bridging function has never been directly demonstrated. Because an alternative protein-mediated bridge between the junctional complex and the cytoplasmic domain of band 3 is also plausible, we have undertaken to characterize the membrane sites to which protein 4.1 can anchor the spectrin and actin skeleton. We demonstrate that proteolytic removal of the cytoplasmic domain of band 3 has minimal effect on the ability of protein 4.1 to promote 125 I-labeled spectrin and actin binding to KI-stripped erythrocyte membrane vesicles. We also show that quantitative blockade of all band 3 sites with either monoclonal or polyclonal antibodies to band 3 is equally ineffective in preventing protein 4.1-mediated association of spectrin and actin with the membrane. In contrast, obstruction of protein 4.1 binding to its docking site on the cytoplasmic pole of glycophorin C is demonstrated to reduce the same protein 4.1 bridging function by ϳ85%. We conclude from these data that (i) glycophorin C contributes the primary anchoring site of the protein 4.1-mediated bridge to the spectrin-actin skeleton; (ii) band 3 is incapable of serving the same function; and (iii) additional minor protein 4.1 bridging sites may exist on the human erythrocyte membrane.

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