YkdA and YvtA, HtrA-like serine proteases in Bacillus subtilis, engage in negative autoregulation and reciprocal cross-regulation of ykdA and yvtA gene expression.

HtrA-type serine proteases participate in folding and degradation of aberrant proteins and in processing and maturation of native proteins. Mutation of the corresponding genes often confers a pleiotropic phenotype that can include temperature sensitivity, sensitivity to osmotic and oxidative stress, and attenuated virulence. There are three HtrA-type serine proteases, YkdA, YvtA, and YycK, encoded in the Bacillus subtilis genome. In this report we show that YkdA and YvtA display many similarities: their expression profiles during the growth cycle in wild-type and mutant backgrounds are very alike, with expression being directed by very similar promoters. Both are induced by temperature upshift and by heterologous amylases at the transition phase of the growth cycle. These characteristics are quite different for YycK, suggesting that it has a cellular function distinct from that of the other two proteases or that it performs the same function but under different conditions. We also show that inactivation of either ykdA or yvtA results in compensating overexpression of the other gene, especially during stress conditions, with a concomitant increase in resistance to heat and hydrogen peroxide stresses. Mutation of both ykdA and yvtA leads to growth defects and to thermosensitivity. The fact that their expression increases dramatically at the transition phase of the growth cycle under certain conditions suggests that the YkdA and YvtA proteases may function in the processing, maturation, or secretion of extracellular enzymes in B. subtilis.

Virilizing adrenal ganglioneuroma containing Leydig cells.

An adrenal medullary ganglioneuroma containing Leydig cells and revealed by a virilizing syndrome in a 56-year old woman is presented. The syndrome, associating with masculinization an elevated serum testosterone level and a normal urinary 17 ketosteroids, is uncommon in adrenal tumours. The tumour was located by computed tomographic (CT) scan and treated by right adrenalectomy. Microscopic examination showed typical features of an adrenal medullary ganglioneuroma containing Leydig cells with Reinke crystalloids. Positive immunohistochemical study confirmed the testosterone secreting nature of the cells. The presence of Leydig cells in the adrenal gland is discussed according embryogenic studies: 1. the common origin of the gonad and the adrenal cortex from the coelomic epithelium, 2. the vicinity of adrenocortical gland and gonad during embryogenesis, 3. the thecal metaplasia of mesenchymal cells, 4. the development of Leydig cells from Schwann cells. Fourth case published in the world literature.