A critical study of the present state of the classification of vibrio-like, curved, microaerophilic bacteria was made. The species originally described under the names Vibrio coli Doyle, V. jejuni Jones et al., V. sputorum PrCvot, and V.bubulus Florent are transferred to the genus Campylobacter Sebald and VCron 1963. The authors suggest that the type species of this genus, C. fetus, be divided into two subspecies: C. fetus subsp. fetus (Smith and Taylor) comb. nov. (syn. V. fetus subsp. intestinalis Florent), which contains the neotype strain of the species, and C. fetus subsp. venerealis (Florent) comb. nov. The previously described subspecies V. fetus subsp. intermedius Elazhari is regarded as an infrasubspecific taxon with the name C. fetus subsp. venerealis biotype intermedius. CIP 5396 ( = A T C C 27374=NCTC 10842) is proposed as the neotype strain of C. fetus subsp. fetus. This strain, then, is also the neotype strain of C. fetus (Smith and Taylor) Sebald and Vkron.In 1913, McFadyean and Stockman (34) discovered a "vibrio" which seemed to be responsible for abortion of pregnant ewes; they obtained an experimental abortion in pregnant cows by inoculation with this organism. Subsequently, Smith (52) recovered a microaere philic "spirillum" from aborted calves. Smith (52) suspected that this organism was identical to that described by McFadyean and Stockman (34). It was designated Vibrio fetus by Smith and Taylor (53), the generic attribution being based on the fact that comma-shaped cells predominate over spirilloid ones, particularly in young cultures.Nevertheless, assignment of this organism t o the genus Vibrio is unsatisfactory: V. fetus differs greatly in phenotypic. respects from the type species of the genus Vibrio, V. cholerae Pacini 1854 (14,24,55). Moreover, the G + C content of the deoxyribonucleic acid (DNA) of

Multiple genes for thioredoxins (TRX) have been demonstrated in Dictyostelium discoideum. We expressed the cDNA for one of these genes (DdTrxl) in E. coli and purified the protein to homogeneity. The interaction with classic substrates as well as TRX reductases was analysed. It reacted with every tested substrate : insulin, NADP-dependent malate dehydrogenase and fructose-1,6-bisphosphatase. With a So.5 of 20 pM, the reactivity with the fructose-l,6-bisphosphatase is the highest ever found for a heterologous TRX. DdTRXl itself is accepted as a substrate by the chloroplast ferredoxindependent TRX reductase, as well as by the E. coli NADPH-dependent TRX reductase. Thus, the Dictyostelium TRX is functionally promiscuous. Its reactivity with insulin, chloroplast NADPdependent malate dehydrogenase and ferredoxin-dependent TRX reductase resemble those of other TRX. It is, however, clearly different in its good interaction with chloroplast fructose-l,6-bisphosphatase and in its poor interaction with E. cnli NADP-dependent TRX reductase.

The first step of the hexosamine pathway is the formation of glucosamine-6-phosphate from fructose-6-phosphate and L-glutamine, a reaction catalyzed by L-glutamine:fructose-6-phosphate amidotransferase (EC 2.6.1.16, amidotransferase) (14). In B. emersonii amidotransferase is a dimer of two apparently identical 76-kDa subunits. This enzyme exists in two forms, which are interconvertible by phosphorylation or dephosphorylation of the serine residue(s) (12,25). Uridine-5'-diphospho-N-acetylglucosamine (UDP-GlcNAc), the end product of hexosamine synthesis and also the substrate for chitin biosynthesis, specifically inhibits the activity of the phosphorylated form of the enzyme (12). In zoospores, the estimated concentration of UDP-GlcNAc (about 400 ,uM) is sufficient to completely inhibit the phosphorylated form of the amidotransferase (Ki for UDP-GlcNAc = 5 ,uM). Early during encystment, dephosphorylation of the enzyme allows it to escape inhibition by 25 (12,25). Although previous observations indicate that the dephosphorylation of amidotransferase is stimulated by magnesium (2, 12, 13), very little is known about the protein phosphatases (PPases) implicated in this process.The purpose of the present study was to characterize the PPases during the life cycle of B. emersondi and to identify those involved in the developmentally regulated control of hexosamine synthesis. To approach this problem we have used an improved procedure described by Cohen and coworkers for identifying and quantifying the serine-threonine PPase types 1, 2A, and 2C (PP1, PP2A, and PP2C) in animal tissues, yeast cells, plants, and protozoans (8, 9, 20, 22). Here we show that these three types of PPases are present in B. emersonii extracts and that amidotransferase is dephosphorylated by both PP2A and PP2C.

A proteolytic fragment (Mr _ 25 000) carrying oniy the aspartokinase activity has been purified by chromatofocusing after limited proteolysis of aspartokinase I-homoserine dehydrogenase I from E.coli K12. The NH,-terminal sequence shows that it corresponds to the amino terminal peptide of the native enzyme. The results confirm a previous hypothesis about the organization of native aspartokinase I-homoserine dehydrogenase I.Aspartokinase I-homoserine dehydrogenase I Limitedproteolysis Gene fusion

A comparison of the data now available on the microorganism variously called C27, Aeromonas shigelloides, Pseudomonas shigelloides, Pseudomonas mich igan i, Plesiomonas sh igelloides, and Fergusonia shigelloides suggests that this organism fits best into the generic description of Vibrio and accordingly should be transferred to this genus as Vibrio shigelloides (Bader) comb. nov.