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PubMed2001

Mycoplasmas, plants, insect vectors: a matrimonial triangle.

Plant pathogenic mycoplasmas were discovered by electron microscopy, in 1967, long after the discovery and culture in 1898 of the first pathogenic mycoplasma of animal origin, Mycoplasma mycoides. Mycoplasmas are Eubacteria of the class Mollicutes, a group of organisms phylogenetically related to Gram-positive bacteria. Their more characteristic features reside in the small size of their genomes, the low guanine (G) plus cytosine (C) content of their genomic DNA and the lack of a cell wall. Plant pathogenic mycoplasmas are responsible for several hundred diseases and belong to two groups: the phytoplasmas and the spiroplasmas. The phytoplasmas (previously called MLOs, for mycoplasma like organisms) were discovered first; they are pleiomorphic, and have so far resisted in vitro cultivation. Phytoplasmas represent the largest group of plant pathogenic Mollicutes. Only three plant pathogenic spiroplasmas are known today. Spiroplasma citri, the agent of citrus stubborn was discovered and cultured in 1970 and shown to be helical and motile. S. kunkelii is the causal agent of corn stunt. S. phoeniceum, responsible for periwinkle yellows, was discovered in Syria. There are many other spiroplasmas associated with insects and ticks. Plant pathogenic mycoplasmas are restricted to the phloem sieve tubes in which circulates the photosynthetically-enriched sap, the food for many phloem-feeding insects (aphids, leafhoppers, psyllids, etc.). Interestingly, phytopathogenic mycoplasmas are very specifically transmitted by leafhoppers or psyllid species. In this paper, the most recent knowledge on phytopathogenic mycoplasmas in relation with their insect and plant habitats is presented as well as the experiments carried out to control plant mycoplasma diseases, by expression of mycoplasma-directed-antibodies in plants (plantibodies).

Animals↗
PubMed1997

Effect of natural amphipathic peptides on viability, membrane potential, cell shape and motility of mollicutes.

The antibiotic activity of ten amphipathic peptides was investigated in six species of mollicutes belonging to the genera Acholeplasma, Mycoplasma and Spiroplasma. A. laidlawii was the most sensitive and M. mycoides subsp. mycoides SC the most resistant. Animal defence peptides (cecropins A and P1, and magainin 2) proved to be less potent than bee-venom mellitin and most of the peptides produced by bacteria (globomycin, gramicidin S, surfactin and valinomycin) or fungi (alamethicin). Gramicidin S was by far the most active peptide, with minimal inhibitory concentrations ranging from 2 to 50 nM. Alamethicin, gramicidin S, mellitin and surfactin had a cidal effect, whilst cecropins, globomycin, magainin 2, polymyxin B and valinomycin proved to be static. The peptides altered the membrane potential of spiroplasma cells with a potency independent of their linear or cyclic structure. However, globomycin depolarized the plasma membrane only weakly, whilst polymyxin B, in order to be active, required prior hyperpolarization of the membrane. The peptides also induced the loss of cell motility and helicity in spiroplasmas, suggesting that motility and cell shape in these bacteria are coupled to the transmembrane electrochemical gradient. Globomycin, an inhibitor of signal-peptidase II, prevented the growth of spiroplasmas, M. gallisepticum, and M. genitalium, but not that of A. laidlawii and M. mycoides subsp. mycoides SC, although the latter also synthesized membrane lipoproteins. Inhibition of spiralin processing by globomycin was demonstrated in S. citri and S. melliferum, with a more pronounced effect in the second species.

Anti-Bacterial Agents↗
PubMed2005

Slow virus disease: deciphering conflicting data on the transmissible spongiform encephalopathies (TSE) also called prion diseases.

The transmissible spongiform encephalopathies (TSE) that manifest as Creutzfeldt-Jakob disease in humans, as scrapie in sheep and goats, mad cow disease in cattle, or chronic wasting disease in cervids (deer) represent a serious human health crisis and a significant economical problem. Despite much research, the nature of the elusive pathogen directly involved with TSE is currently unresolved. This article reviews current pathogen-cell plasma membrane properties, showing that the primary biochemical marker of the prion disease is used as a receptor by the intracellular bacterium Brucella abortus. Such observation makes plausible the role for the prion in the pathogenesis of TSE, and supports the concept that Spiroplasma, a wall-less bacterium, may be a transmissible agent of TSE. Over the past three decades, we have published convincing evidence that Spiroplasma infection is associated with TSE. The bacterial-prion-receptor concept by other laboratories support a model for TSE wherein a Spiroplasma bacterium can bind to prion receptors (alone or with anchors) on the cell surface lipid raft, allowing entry of the microbe into the cell to initiate infection. The relevance of this new concept is that it offers a new window for future research involving a bacterium in the pathogenesis of TSE. Data from the bacterial-prion-receptor model will aid in the development diagnostic tests and/or treatment protocols for TSE.

Animals↗
PubMed2002

Secondary structure of spiralin in solution, at the air/water interface, and in interaction with lipid monolayers.

The surface of spiroplasmas, helically shaped pathogenic bacteria related to the mycoplasmas, is crowded with the membrane-anchored lipoprotein spiralin whose structure and function are unknown. In this work, the secondary structure of spiralin under the form of detergent-free micelles (average Stokes radius, 87.5 A) in water and at the air/water interface, alone or in interaction with lipid monolayers was analyzed. FT-IR and circular dichroism (CD) spectroscopic data indicate that spiralin in solution contains about 25+/-3% of helices and 38+/-2% of beta sheets. These measurements are consistent with a consensus predictive analysis of the protein sequence suggesting about 28% of helices, 32% of beta sheets and 40% of irregular structure. Brewster angle microscopy (BAM) revealed that, in water, the micelles slowly disaggregate to form a stable and homogeneous layer at the air/water interface, exhibiting a surface pressure up to 10 mN/m. Polarization modulation infrared reflection absorption spectroscopy (PMIRRAS) spectra of interfacial spiralin display a complex amide I band characteristic of a mixture of beta sheets and alpha helices, and an intense amide II band. Spectral simulations indicate a flat orientation for the beta sheets and a vertical orientation for the alpha helices with respect to the interface. The combination of tensiometric and PMIRRAS measurements show that, when spiroplasma lipids are used to form a monolayer at the air/water interface, spiralin is adsorbed under this monolayer and its antiparallel beta sheets are mainly parallel to the polar-head layer of the lipids without deep perturbation of the fatty acid chains organization. Based upon these results, we propose a 'carpet model' for spiralin organization at the spiroplasma cell surface. In this model, spiralin molecules anchored into the outer leaflet of the lipid bilayer by their N-terminal lipid moiety are composed of two colinear domains (instead of a single globular domain) situated at the lipid/water interface. Owing to the very high amount of spiralin in the membrane, such carpets would cover most if not all the lipids present in the outer leaflet of the bilayer.

Air↗
PubMed1997

Effects on mollicutes (wall-less bacteria) of synthetic peptides comprising a signal peptide or a membrane fusion peptide, and a nuclear localization sequence (NLS) -- a comparison with melittin.

In order to investigate the effect of primary amphipathic peptides on mollicutes (wall-less bacteria), we have synthesised five molecules (P1, P2, P3, JM123, and JM133) comprising a 16 to 18-residue hydrophobic sequence and the nuclear localization sequence (NLS) PKKKRKV of simian virus 40 large-T antigen, C-terminated by a cysteamide group. The hydrophobic cluster was in P1 the signal sequence of the heavy chain of Caiman crocodilus immunoglobulin G and in JM123 the fusion peptide of human immunodeficiency virus 1 glycoprotein gp41 in which phenylalanine7 was replaced by a tryptophan residue. The homologues P2, P3, and JM133 were obtained by slight alterations of these sequences. Circular dichroism spectroscopy revealed that, in liposomes, P-series peptides were mainly under the form of beta-sheets whereas JM-series peptides displayed a high proportion of turns. These peptides proved to be bactericidal for some mollicutes, notably Acholeplasma laidlawii, but were much less potent than melittin. Furthermore, their antibiotic activity was independent of the average thickness of the plasma membrane hydrophobic core whilst that of melittin was inversely related to the thickness. Melittin and the synthetic peptides abolished spiroplasma cell motility and helicity, but only melittin and P-series peptides split the cells into globular forms displaying an average diameter of ca. 1 microm. In contrast to melittin, the synthetic peptides agglutinated spiroplasmas, suggesting that their polycationic NLS was exposed on the cell surface. P-series peptides decreased, though less efficiently than melittin, A. laidlawii and Spiroplasma melliferum membrane potential (delta psi) and transmembrane pH gradient (delta pH), at concentrations much lower than their minimal inhibitory concentrations whilst JM-series peptides had no effect on delta psi and delta pH in the same conditions. Actually, the bactericidal activity of these peptides towards mollicutes was proportional to their ability to collapse the electrochemical transmembrane potential.

Alligators and Crocodiles↗
PubMed1998

Membrane permeabilisation and antimycoplasmic activity of the 18-residue peptaibols, trichorzins PA.

The membrane permeabilisation properties of six linear natural 18-residue peptaibols, termed trichorzins PA, have been assessed on liposomes and on mollicutes (trivial name, mycoplasmas), a class of parasitic bacteria characterized by a small genome, the lack of a cell wall, a minute cell size, and the incorporation in their plasma membrane of exogenously supplied cholesterol. The trichorzins PA used in this study (PA II, PA IV-VI, PA VIII, and PA IX) differ between them by amino acid or amino alcohol substitutions at positions 4, 7, and 18, and form slightly amphipathic alpha-helices. They proved bactericidal for mollicutes belonging to the genera Acholeplasma, Mycoplasma, and Spiroplasma, with minimal inhibitory concentrations (3.12</=MICs</=50 microM) generally 2 to 4 fold higher than those of alamethicin F50, a related 20-residue peptide (1.56</=MICs</=12.5 microM). Spiroplasma cells were apparently not protected by the presence of spiralin on their surface. The activities of the six trichorzins PA were not influenced by their sequence variations and no synergistic effect was observed. Consistent with the marginal effect of cholesterol on the incorporation of the trichorzins PA into liposome bilayers, the antibiotic activity was independent of the amount of cholesterol in the membranes of the different mollicutes. The trichorzins PA and alamethicin inhibited the motility of Spiroplasma melliferum, the helical cells being deformed and split into coccoid forms. Membrane potential measurements in Acholeplasma laidlawii and S. melliferum showed that trichorzin PA V and alamethicin F50 very efficiently depolarized the plasma membrane of mollicutes. This was consistent with fluorescence and 23Na NMR measurements on liposomes that revealed the permeabilisation of the lipid bilayer and the nonselective ionophoric activity of the trichorzins PA. These data suggest that the bactericidal activity exhibited by the trichorzins PA on mollicutes is due to the permeabilisation of the plasma membrane.

Alamethicin↗
PubMed2002

Diversity and geographic distribution of secondary endosymbiotic bacteria in natural populations of the pea aphid, Acyrthosiphon pisum.

In addition to the essential intracellular symbiotic bacterium Buchnera, several facultative endosymbiotic bacteria called collectively secondary symbionts (S-symbionts) have been identified from the pea aphid Acyrthosiphon pisum. We conducted an extensive and systematic survey of S-symbionts in Japanese local populations of A. pisum using a specific PCR detection technique. Five S-symbionts of A. pisum, PASS, PAUS, PABS, Rickettsia and Spiroplasma, and two facultative endosymbionts universally found in various insects, Wolbachia and Arsenophonus, were targeted. Of 119 isofemale strains originating from 81 localities, 66.4% of the strains possessed either of four S-symbionts: PASS (38.7%); PAUS (16.0%); Rickettsia (8.4%); and Spiroplasma (3.4%), while 33.6% of the strains contained only Buchnera. PABS, Wolbachia and Arsenophonus were not detected from the Japanese strains of A. pisum. In order to understand intra- and interpopulational diversity of S-symbiont microbiota in detail, 858 insects collected from 43 localities were examined for infection with the four S-symbionts. It was demonstrated that different S-symbionts coexist commonly in the same local populations, but double infections with two S-symbionts were rarely detected. Notably, the S-symbionts exhibited characteristic geographical distribution patterns: PASS at high frequencies all over Japan; PAUS at high frequencies mainly in the northeastern part of Japan; and Rickettsia and Spiroplasma at low frequencies sporadically in the southwestern part of Japan. These results indicate that the geographical distribution and infection frequency of the S-symbionts, in particular PAUS, might be affected by environmental and/or historical factors. Statistical analyses suggested that the distribution of PAUS infection might be related to host plant species, temperature and precipitation.

Animals↗
PubMed1977

Spiroplasmavirus citri 3: propagation, purification, proteins, and nucleic acid.

SVC3 is a short-tailed polyhedral virus particle morphologically detectable in many spiroplasmas. It was isolated from two different spiroplasmas (Spiroplasma citri and the suckling mouse cataract agent) by infecting lawns and broth culture of another strain of Spiroplasmavirus citri. Virions from either donor strain had a buoyant density of 1.26 grams per cubic centimeter (metrizamide) or 1.45 grams per cubic centimeter (cesium chloride), and contained five proteins and linear double-stranded DNA with a molecular weight of 14 X 10(6). Other spiroplasmaviruses have not been propagated, and the molecular weights of double-stranded DNA from other mycoplasma (Acholeplasma) viruses are unknown.

Bacteriophages↗
PubMed2000

Endosymbiotic microbiota of the bamboo pseudococcid Antonina crawii (Insecta, Homoptera).

We characterized the intracellular symbiotic microbiota of the bamboo pseudococcid Antonina crawii by performing a molecular phylogenetic analysis in combination with in situ hybridization. Almost the entire length of the bacterial 16S rRNA gene was amplified and cloned from A. crawii whole DNA. Restriction fragment length polymorphism analysis revealed that the clones obtained included three distinct types of sequences. Nucleotide sequences of the three types were determined and subjected to a molecular phylogenetic analysis. The first sequence was a member of the gamma subdivision of the division Proteobacteria (gamma-Proteobacteria) to which no sequences in the database were closely related, although the sequences of endosymbionts of other homopterans, such as psyllids and aphids, were distantly related. The second sequence was a beta-Proteobacteria sequence and formed a monophyletic group with the sequences of endosymbionts from other pseudococcids. The third sequence exhibited a high level of similarity to sequences of Spiroplasma spp. from ladybird beetles and a tick. Localization of the endosymbionts was determined by using tissue sections of A. crawii and in situ hybridization with specific oligonucleotide probes. The gamma- and beta-Proteobacteria symbionts were packed in the cytoplasm of the same mycetocytes (or bacteriocytes) and formed a large mycetome (or bacteriome) in the abdomen. The spiroplasma symbionts were also present intracellularly in various tissues at a low density. We observed that the anterior poles of developing eggs in the ovaries were infected by the gamma- and beta-Proteobacteria symbionts in a systematic way, which ensured vertical transmission. Five representative pseudococcids were examined by performing diagnostic PCR experiments with specific primers; the beta-Proteobacteria symbiont was detected in all five pseudococcids, the gamma-Proteobacteria symbiont was found in three, and the spiroplasma symbiont was detected only in A. crawii.

Animals↗
PubMed1986

Probable insensitivity of mollicutes to rifampin and characterization of spiroplasmal DNA-dependent RNA polymerase.

The effect of rifampin on five mollicutes (Spiroplasma citri, Spiroplasma melliferum, Spiroplasma apis, Acholeplasma laidlawii, and Mycoplasma mycoides) was compared with that on Escherichia coli. We found that, in contrast to wild-type E. coli, mollicutes were insensitive to rifampin. DNA-dependent RNA polymerases from S. melliferum and S. apis were purified to the stage where the enzymes were dependent on the addition of exogenous templates for activity. The enzymes were then tested for their sensitivity to rifampin. Spiroplasmal enzymes were at least 1,000 times less sensitive to rifampin than the corresponding E. coli enzyme. This result provides a molecular basis for the resistance of mollicutes to rifampin. The RNA polymerase of S. melliferum was further purified and its subunit composition was investigated. The RNA polymerase has one small and two large subunits. The structure of S. melliferum RNA polymerase therefore resembles that of the eubacterial enzymes in spite of its insensitivity to rifampin.

Acholeplasma laidlawii↗
PubMed1978

Effect of osmotic potential, pH, and temperature on the growth of a helical, motile mycoplasma causing corn stunt disease.

Growth characteristics of corn stunt spiroplasma, a helical, motile mycoplasma, were studied over a range of osmolality, pH, and temperature in a simple medium containing 20% (v/v) agamma horse serum, 1.5% (w/v) PPLO broth, and various concentrations of sucrose. The spiroplasma was able to grow in a wide spectrum of osmolalities from 360 to 1120 mosm. Optimal growth was observed in media that contained 0.25-0.35 M sucrose. The organism became longer and thinner in media adjusted to 0.65 M sucrose or more. The spiroplasma lost helicity and motility immediately after transfer to media at pH 5.4 or lower. Optimal pH for growth was 7.2. No growth was observed at pH lower than 5.4 or higher than 8.0. Optimal temperature for growth was 32 degrees C. Very little or no growth was observed at temperatures lower than 15 degrees C or higher than 35 degrees C.

Culture Media↗
PubMed1987

In vitro detection of plant mycoplasmas by immunofluorescent staining with monoclonal antibodies.

Hybridoma techniques have been applied to develop specific monoclonal antibodies (McAbs) against spiroplasmas and mycoplasma-like organisms (MLOs). Advantages of the McAbs have been clearly demonstrated in the detection of aster yellows (AY) MLO by indirect enzyme-linked immunosorbent assay (ELISA) and immunofluorescent staining, compared with conventionally produced polyclonal antibodies. McAbs have also been applied in the in vitro detection and identification of spiroplasmas and AY MLOs on membrane filters using modified direct-count immunofluorescent staining. Organisms were fixed with glutaraldehyde and treated with McAbs and fluorescein isothiocyanate (FITC)-conjugated antimouse immunoglobulin, by incubating and concentrating them in a microcentrifuge tube before collecting them on polycarbonate membrane. This procedure best conserves the helical integrity of spiroplasmas without altering the configuration of surface antigens recognized by McAbs. This method could be valuable in monitoring the fastidious mycoplasmas during purification or cultivation attempts.

Antibodies, Bacterial↗
PubMedDate not supplied

The Emmy Klieneberger-Nobel Award lecture. Reflections on recovery of some fastidious mollicutes with implications of the changing host patterns of these organisms.

Major advances have occurred the past few years in the cultivation of a number of new, fastidious mollicutes--events which can be traced directly to successful efforts to develop culture media for the expanding group of helical mollicutes (spiroplasmas) inhabiting plants and arthropods. A description of cultivation techniques successful in primary isolation of three unusual mollicutes, representing new mycoplasmas from man and animals and a new spiroplasma from ticks, emphasizes some important factors in recovery of wall-less prokaryotes with special cultural requirements. Vigorous efforts to understand the distribution of spiroplasmas in plant and insect hosts also led to the cultivation of new, non-helical mollicutes. Preliminary characterization of a number of these new agents offers strong evidence for a unique and distinct Acholeplasma and Mycoplasma flora of both plants and insects.

Acholeplasma↗
PubMed1996

Reduction of benzyl viologen distinguishes genera of the class Mollicutes.

We tested the ability of 62 growing strains belonging to the class Mollicutes to reduce the redox indicator and free-radical generator 1,1'-dibenzyl-4,4'-bipyridinium dichloride (benzyl viologen [BV]) to a blue-violet-purple color. BV was reduced by 12 Acholeplasma species but not by Acholeplasma multiforme PN525T (T = type strain). BV was also reduced by five of nine Mesoplasma species and by four of six Entomoplasma species. BV was not reduced by 19 Mycoplasma species, six Spiroplasma species, five unnamed Spiroplasma strains belonging to different serogroups, three Ureaplasma species, and one unnamed Ureaplasma strain. The BV-reducing ability was localized in the membrane of Acholeplasma laidlawii B-PG9 and was dependent on NADH. Reduction of BV could be expressed in mixed cultures, and this activity may be useful for recognizing the contaminating presence of an Acholeplasma species. The reductive BV response may have phylogenetic value. We believe that the test described in this paper readily distinguishes all Acholeplasma species and some Mesoplasma and Entomoplasma species from all Mycoplasma, Spiroplasma, and Ureaplasma species tested.

Benzyl Viologen↗
PubMed1989

A phylogenetic analysis of the mycoplasmas: basis for their classification.

Small-subunit rRNA sequences were determined for almost 50 species of mycoplasmas and their walled relatives, providing the basis for a phylogenetic systematic analysis of these organisms. Five groups of mycoplasmas per se were recognized (provisional names are given): the hominis group (which included species such as Mycoplasma hominis, Mycoplasma lipophilum, Mycoplasma pulmonis, and Mycoplasma neurolyticum), the pneumoniae group (which included species such as Mycoplasma pneumoniae and Mycoplasma muris), the spiroplasma group (which included species such as Mycoplasma mycoides, Spiroplasma citri, and Spiroplasma apis), the anaeroplasma group (which encompassed the anaeroplasmas and acholeplasmas), and a group known to contain only the isolated species Asteroleplasma anaerobium. In addition to these five mycoplasma groups, a sixth group of variously named gram-positive, walled organisms (which included lactobacilli, clostridia, and other organisms) was also included in the overall phylogenetic unit. In each of these six primary groups, subgroups were readily recognized and defined. Although the phylogenetic units identified by rRNA comparisons are difficult to recognize on the basis of mutually exclusive phenotypic characters alone, phenotypic justification can be given a posteriori for a number of them.

Base Sequence↗
PubMed1998

Mollicutes-wall-less bacteria with internal cytoskeletons.

The structure and motility of the Mollicutes (Spiroplasma, Mycoplasma, and Acholeplasma) are briefly reviewed. The data are presented from the perspective of prokaryotic and eukaryotic motors, cytoskeletons, and cell motility. The Mollicutes are eubacteria derived from Clostridia by regressive evolution and genome reduction to produce the smallest and simplest free-living and self-replicating cells. Structurally, the Mollicutes are characterized by a complete lack of a cell wall and the presence of an internal cytoskeleton. Spiroplasma, which are helical cells with a flat, ribbon-like cytoskeleton, are amenable to structural and geometrical analysis. Motility and shape changes can be explained and modeled by the cytoskeleton acting as a linear motor.

Acholeplasma↗
PubMed1977

Lipoquinones of some bacteria and mycoplasmas, with considerations on their functional significance.

In a comparative study the lipoquinones of some chemoorganotrophic, facultatively aerobic bacteria, and representative Acholeplasma, Mycoplasma, Spiroplasma, and Thermoplasma strains were investigated. The quinones were partly purified by preparative thin layer chromatography of lipid extracts, and characterized by their difference spectra (reduced minus oxidized) and Rf values. Respiring bacteria expectedly contained benzoquinones and/or naphthoquinones in micromolar concentrations whereas some aerotolerant, cytochrome-less, gram-positive bacteria were found to contain menaquinones in nanomolar concentrations, or even no quinones; only Streptococcus faecalis, an organism supposed to use a rudimentary, flavin-terminated respiratory chain system produced desmethyl menaquinone in amounts ranging between "high" and "low" quinone contents. Among the mycoplasmas investigated, only Thermoplasma acidophilum was found to be capable of synthesizing quinones (MK-7) in the micromolar order of magnitude indicating a respiratory electron transport system. The presence of energetically useful respiratory chain systems in Acholeplasma, Mycoplasma, and Spiroplasma is questioned since these organisms contain quinones (MK-4) in nanomolar concentrations, or no quinones, depending on the presence of exogeneous MK-6 in the growth medium. The possible metabolite role of menaquinones present in "low" amounts, as well as the role of NADH oxidase systems more or less tightly bound to the cytoplasmic membrane with the mycoplasmas deserves further investigation.

Bacillus cereus↗
PubMed1996

Inhibition of spiralin processing by the lipopeptide antibiotic globomycin.

The cyclic lipopeptide globomycin, a specific inhibitor of signal-peptidase II (Lsp A), proved toxic for the mollicute Spiroplasma melliferum with a minimal inhibitory concentration (MIC) in the range 6.25-12.5 microM, about one order of magnitude higher (that is, less efficient) than bee-venom mellitin. SDS-PAGE analysis of cell proteins followed by immunolabeling ("Western blotting") and by crossed immunoelectrophoresis demonstrated that the cleavage of the prespiralin leader peptide was prevented by globomycin. Cell fractionation experiments showed that prespiralin was membrane bound and did not accumulate in the cytoplasm or in the culture medium. Furthermore, the use of the potential-sensitive fluorescent dye 3,3'-dipropyl-2,2'-thiadicarbocyanine iodide (diS-C3-[5]) revealed that, in contrast to valinomycin and mellitin, globomycin up to 30 microM has no effect on the electrical transmembrane potential of S. melliferum. This indicates that the toxicity of globomycin for spiroplasma cells is mainly if not exclusively owing to the inhibition of spiralin processing. Added to previously published data, these results suggest that spiralin and probably other lipoproteins of mollicutes are acylated and membrane targeted by a mechanism involving notably the processing of the prelipoprotein precursor by a type II, globomycin-sensitive signal peptidase.

Anti-Bacterial Agents↗