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Staphylococcus aureus and Streptococcus pyogenes express pyrogenic toxin superantigens (PTSAgs) that are associated with toxic shock syndrome (TSS) and staphylococcal food poisoning (SFP). Most PTSAgs cause TSS in deep-tissue infections, whereas only TSS toxin 1 (TSST-1) is associated with menstrual, vaginal TSS. In contrast, SFP has been linked only with staphylococcal enterotoxins (SEs). Because of the differential abilities of PTSAgs to cause systemic or localized symptoms in a site-dependent manner, the present study was undertaken to assess the toxins' abilities to cross mucosal barriers. The activity of three PTSAgs when delivered orally, vaginally, or intravenously to rabbits and orally to monkeys was investigated. TSST-1 induced shock via all three routes in rabbits. Although active when administered intravenously, SEC1 and streptococcal pyrogenic exotoxin A (SPEA) did not cause symptoms when administered orally or vaginally. Only SEC1 induced emesis in the monkey feeding assay. TSST-1, albeit less stable than SEC1 and SPEA to pepsin, induced diarrhea in monkeys. Our results may explain the unique association of TSST-1 with menstrual TSS and why SPEA is only rarely associated with TSS after pharyngitis, despite being highly associated with TSS after subcutaneous infections. Finally, our studies indicate that enterotoxicity in SFP is not the result of superantigenicity.

Cytochrome c1 is a component of the mitochondrial respiratory chain in most eukaryotes. The protein is coded by nuclear DNA, synthesized as a larger precursor outside the mitochondria and then cleaved to the mature form in two successive steps during its import into the mitochondria. We have cloned the structural gene for yeast cytochrome c1 by functional complementation of a cytochrome c1‐deficient yeast mutant with a yeast genomic library in the yeast‐Escherichia coli ‘shuttle’ vector YEp 13. The complete nucleotide sequence of the gene and of its 5′‐ and 3′‐flanking regions was determined. The deduced amino acid sequence of the yeast cytochrome c1 precursor reveals an unusually long transient amino‐terminal presequence of 61 amino acids. This presequence consists of a strongly basic amino‐terminal region of 35 amino acids, a central region of 19 uncharged amino acids and an acidic carboxy‐terminal region of seven amino acids. This tripartite structure of the presequence resembles that of the precursor of cytochrome c peroxidase and supports a previous suggestion on the import pathways of these two precursors.

The first 74 amino acids of the yeast GAL4 gene product are sufficient to localize a GAL4-beta-galactosidase chimeric protein to the yeast nucleus. Chimeric proteins missing the first 74 GAL4 amino acids, but containing almost all of the rest of GAL4, are not localized to the nucleus and are expressed at higher levels than their nuclear counterparts. On this basis, point mutations within GAL4, which reduce nuclear localization and increase production of a normally nuclear GAL4-beta-galactosidase fusion protein, were isolated and sequenced. The effect of these mutations on the localization and expression of the intact GAL4 protein was examined. The degree to which the mutant proteins are excluded from the nucleus varies, but all mutations cause overproduction of the protein. Point mutations altering two of the six cysteine residues of the GAL4 putative 'zinc finger' abolish gene activation by intact GAL4; however, mutations in nearby residues have no effect on GAL4-dependent gene activation.

Previous work (Molec. Phys., 64, 165) on symmetry breaking in HD+ has been extended to include further nuclear motion effects in an adiabatic approximation. After a second unitary transformation the only operator involving derivatives with respect to R remaining in the hamiltonian is [image omitted]. It is shown that the new hamiltonian corresponds to an hamiltonian in hyperspheroidal coordinates; the relationship to other work is pointed out. Calculations on the vibration-rotation levels of HD+ using the transformed hamiltonian are reported and discussed.

Full variational calculations for the vibration-rotation levels of the ground electronic state of HD+ are reported. All nonadiabatic coupling terms are retained in the hamiltonian and both Σ and Π functions are included in the basis, so that coupling of electronic and rotational angular momentum is accounted for; Fues-type functions are used in the vibrational basis. The results, which include high J levels but are limited to low ν, are for ν = 0, J ˇ- 46; ν = 1, J ˇ- 43; ν = 2, J ˇ- 38; ν = 3, ν = 4, J = 0. Where comparison is possible, the agreement with previous calculations is good and agreement with experiment is excellent.

By performing a unitary transformation on the hamiltonian for HD+, the g/u symmetry breaking term in the kinetic energy is eliminated completely. The resulting transformed hamiltonian is interpreted in terms of effective nuclear charges and an effective nuclear reduced mass. The transformation is performed prior to conversion to internal coordinates, so that the theory applies to states of any Λ and J, and is also selected so that the transformed electron-nuclear potential energy and the transformed operators for the electron densities at the nuclei have simple forms, suitable for computation. It is shown that the transformed equation gives the correct dissociation energies for all states of HD+ and the correct atomic electron densities at the nucleus at dissociation; these exact results are obtained from a purely electronic equation, in which no derivatives with respect to internuclear separation appear, so that no adiabatic or nonadiabatic corrections are needed. The transformed hamiltonian is used in calculations described in the following paper.

The transformed Schrödinger equation, in which the g/u symmetry breaking terms appear in the potential energy, is solved in an adiabatic approximation to give vibration-rotation energies and vibrationally averaged Fermi contact parameters near dissociation for the ground and first excited states of HD+. The electronic part of the equation is solved variationally, using basis functions modelled on the Hylleraas expansion. These results are found to be in close agreement with those from a coupled states calculation, for which improved values for other hyperfine parameters are also given. By extending the range of integration in the numerical solution of the vibration-rotation equation, the highest bound levels of HD+ are found to be v=22, J=1 for the ground electronic state and v=1, J=0 for the first excited state.

Symmetry breaking corrections for HD+ are estimated by performing a unitary transformation on the hamiltonian. The terms responsible for g/u coupling are removed from the kinetic energy operator at the expense of introducing additional terms in the potential. The effective electrostatic potential may be interpreted in terms of effective nuclear charges. A new hamiltonian having the correct dissociation limits is obtained and the corresponding Schrödinger equation is largely separable. The resulting corrections to the energy compare well with previous work, particularly at large bond lengths, and the electric dipole moment and electron densities at the nuclei show the correct behaviour near dissociation.

A variety of peptides can mediate the localization of proteins to the nucleus. We have identified yeast proteins of 70 and 59 kD that bind to nuclear localization peptides of SV-40 T antigen, Xenopus nucleoplasmin, and the yeast proteins Ga14 and histone H2B. These proteins are assayed by the binding of peptide-albumin conjugates to proteins immobilized on nitrocellulose filters. These binding proteins fractionate with nuclei and are extractable with salt but not detergent. Radiolabeled peptide-albumin conjugates also bind to isolated nuclei; the binding is saturable and can be extracted with salt. Different nuclear localization peptides compete with each other, implying that a single class of proteins is responsible for their recognition. The 70- and 59-kD proteins have the properties expected for a receptor that would act to direct proteins to the nucleus.