The C-terminus of p63 contains multiple regulatory elements with different functions.

The transcription factor p63 is expressed as at least six different isoforms, of which two have been assigned critical biological roles within ectodermal development and skin stem cell biology on the one hand and supervision of the genetic stability of oocytes on the other hand. These two isoforms contain a C-terminal inhibitory domain that negatively regulates their transcriptional activity. This inhibitory domain contains two individual components: one that uses an internal binding mechanism to interact with and mask the transactivation domain and one that is based on sumoylation. We have carried out an extensive alanine scanning study to identify critical regions within the inhibitory domain. These experiments show that a stretch of ∼13 amino acids is crucial for the binding function. Further, investigation of transcriptional activity and the intracellular level of mutants that cannot be sumoylated suggests that sumoylation reduces the concentration of p63. We therefore propose that the inhibitory function of the C-terminal domain is in part due to direct inhibition of the transcriptional activity of the protein and in part due to indirect inhibition by controlling the concentration of p63.

The active site of the thermophilic CYP119 from Sulfolobus solfataricus.

CYP119 from Sulfolobus solfataricus, the first thermophilic cytochrome P450, is stable at up to 85 degrees C. UV-visible and resonance Raman show the enzyme is in the low spin state and only modestly shifts to the high spin state at higher temperatures. Styrene only causes a small spin state shift, but T(1) NMR studies confirm that styrene is bound in the active site. CYP119 catalyzes the H(2)O(2)-dependent epoxidation of styrene, cis-beta-methylstyrene, and cis-stilbene with retention of stereochemistry. This catalytic activity is stable to preincubation at 80 degrees C for 90 min. Site-specific mutagenesis shows that Thr-213 is catalytically important and Thr-214 helps to control the iron spin state. Topological analysis by reaction with aryldiazenes shows that Thr-213 lies above pyrrole rings A and B and is close to the iron atom, whereas Thr-214 is some distance away. CYP119 is very slowly reduced by putidaredoxin and putidaredoxin reductase, but these proteins support catalytic turnover of the Thr-214 mutants. Protein melting curves indicate that the thermal stability of CYP119 does not depend on the iron spin state or the active site architecture defined by the threonine residues. Independence of thermal stability from active site structural factors should facilitate the engineering of novel thermostable catalysts.

Occupational lead exposure aboard a tall ship.

To evaluate occupational exposures to lead in shipfitters cutting and riveting lead-painted iron plates aboard an iron-hulled sailing vessel, we conducted an environmental and medical survey. Lead exposures in seven personal (breathing zone) air samples ranged from 108 to 500 micrograms/m3 (mean 257 micrograms/m3); all were above the Occupational Safety and Health Administration (OSHA) standard of 50 micrograms/m3. In two short-term air samples obtained while exhaust ventilation was temporarily disconnected, mean lead exposure rose to 547 micrograms/m3. Blood lead levels in ten shipfitters ranged from 25 to 53 micrograms/dl (mean, 37.8 micrograms/dl); levels in three of these workers exceeded the upper normal limit of 40 micrograms/dl. Blood lead levels in shipfitters were significantly higher than in other shipyard workers (mean 10.0 micrograms/dl; p less than 0.001). Smoking shipfitters (mean, 47 micrograms/dl) had significantly higher lead levels than nonsmokers (mean, 32 micrograms/dl; p = 0.03). Lead levels in shipfitters who wore respirators were not lower than in those who wore no protective gear (p = 0.68). Four shipfitters had erythrocyte protoporphyrin (EP) concentrations above the adult upper normal limit of 50 micrograms/dl. A close correlation was found between blood lead and EP levels (r = 0.70). Prevalence of lead-related symptoms was no higher in shipfitters than in other workers. No cases of symptomatic lead poisoning were noted. These data indicate that serious occupational exposure to lead can occur in a relatively small boatyard.

Epidemic kepone poisoning in chemical workers.

From March 1974 through July 1975, 76 (56%) of 133 persons who had worked at a pesticide plant that produced Kepone, a chlorinated hydrocarbon insecticide, contracted a previously unrecognized clinical illness characterized by nervousness, tremor, weight loss, opsoclonus, pleuritic and joint pain, and oligospermia. Illness incidence rates for production workers (64%) were significantly higher than for nonproduction personnel (16%). The mean blood Kepone level for workers with illness was 2.53 ppm and for those without disease 0.60 ppm (p less than 0.001). Blood Kepone levels in current workers (mean, 3.12 ppm) were higher than those in former employees (1.22 ppm). Blood Kepone levels for workers in nearby businesses and for residents of a community within 1.6 km of the plant ranged from undetectable to 32.5 ppb. Illness attributable to Kepone was found in two wives of Kepone workers; there was no apparent association between frequency of symptoms and proximity to the plant in the survey of the community population.

PIP: From March 1974-July 1975, 76 (57%) of 133 persons who had worked at a pesticide plant that produced Kepone, a chlorinated hydrocarbon insecticide, contracted a previously unrecognized clinical illness characterized by nervousness, tremor, weight loss, opsoclonus, pleuritic and joint pain, and oligospermia. Illness incidence rates for production workers (64%) were significantly higher than for nonproduction personnel (16%). The mean blood Kepone level for workers with illness was 2.53 ppm and for those without disease 0.60 ppm (p0.001). Blood Kepone levels in current workers (mean, 3.12 ppm) were higher than those in former employees (1.22 ppm). Blood Kepone levels for workers in nearby businesses and for residents of a community within 1.6 km of the plant ranged from undetectable to 32.5 ppb. Illness attributable to Kepone was found in wives of 2 Kepone workers; there was no apparent association between frequency of symptoms and proximity to the plant in the survey of the community population.