Expression of apoptosis regulatory proteins of the Bcl-2 family and p53 in primary resected non-small-cell lung cancer

Proteins of the Bcl-2 family as well as p53 are important regulators of apoptosis. Alterations in the expression of these proteins can contribute to the formation of cancer, as well as influence tumour response to chemo- and radiotherapy. We used antibodies specific for the human Bcl-2, Mcl-1, Bax, Bak and p53 proteins to examine the expression of these apoptosis-regulating genes in 49 archival specimens of patients with radically resected non-small-cell lung cancer (NSCLC). Tumour cells containing immunostaining for the antiapoptotic proteins Bcl-2 and Mcl-1 were present in 31% and 58% of the cases evaluated, respectively, whereas immunopositivity for the proapoptotic proteins Bax and Bak was found in 47% and 58% of the samples. p53 immunopositivity was detected in 61% of the samples. The expression of Bcl-2 and p53 and the expression of Mcl-1 and Bax showed a positive association (P= 0.02 and P= 0.06 respectively), whereas the expression of Bax was inversely related to p53 (P= 0.008). The expression of Bcl-2 had a negative influence on relapse-free survival in this population of primary resected NSCLC patients (P= 0.02). The expression of p53 and Bcl-2 was significantly associated with metastasis-free survival (P< 0.01). Only patients with p53-positive tumours developed metastases during the follow-up period. Our results establish the frequent expression of the Bcl-2 family proteins Bcl-2, Mcl-1, Bax and Bak in NSCLC. It can be expected that Bcl-2 family members have no straightforward impact on clinical outcome in this disease because their interactions in the regulation of apoptosis are complex. © 1999 Cancer Research Campaig

Essential role of Isd11 in mitochondrial iron–sulfur cluster synthesis on Isu scaffold proteins

Mitochondria are indispensable for cell viability; however, major mitochondrial functions including citric acid cycle and oxidative phosphorylation are dispensable. Most known essential mitochondrial proteins are involved in preprotein import and assembly, while the only known essential biosynthetic process performed by mitochondria is the biogenesis of iron–sulfur clusters (ISC). The components of the mitochondrial ISC-assembly machinery are derived from the prokaryotic ISC-assembly machinery. We have identified an essential mitochondrial matrix protein, Isd11 (YER048w-a), that is found in eukaryotes only. Isd11 is required for biogenesis of cellular Fe/S proteins and thus is a novel subunit of the mitochondrial ISC-assembly machinery. It forms a complex with the cysteine desulfurase Nfs1 and is required for formation of an Fe/S cluster on the Isu scaffold proteins. We conclude that Isd11 is an indispensable eukaryotic component of the mitochondrial machinery for biogenesis of Fe/S proteins

Structural aspects of the cytochromeb 6 f complex; structure of the lumen-side domain of cytochromef

The following findings concerning the structure of the cytochrome b(6)f complex and its component polypeptides, cyt b(6), subunit IV and cytochrome f 1. Comparison of the amino acid sequences of 13 and 16 cytochrome b(6) and subunit IV polypeptides, respectively, led to (a) reconsideration of the helix lengths and probable interface regions, (b) identification of two likely surface-seeking helices in cyt b(6) and one in SU IV, and (c) documentation of a high degree of sequence invariance compared to the mitochondrial cytochrome. The extent of identity is particularly high (88% for conserved and pseudo- conserved residues) in the segments of cyt b(6) predicted to be extrinsic on the n-side of the membrane. 2. The intramembrane attractive forces between trans-membrane helices that normally stabilize the packing of integral membrane proteins are relatively weak. 3. The complex isolated in dimeric form has been visualized, along with isolated monomer, by electron microscopy. The isolated dimer is much more active than the monomer, is the major form of the complex isolated and purified from chloroplasts, and is inferred to be a functional form in the membrane. 4. The isolated cyt b(6)f complex contains one molecule of chlorophyll a. 5. The structure of the 252 residue lumen-side domain of cytochrome f isolated from turnip chloroplasts has been solved by X-ray diffraction analysis to a resolution of 2.3 Å