Functional independence of the protein translocation machineries in mitochondrial outer and inner membranes

The protein translocation machineries of the outer and inner mitochondrial membranes usually act in concert during translocation of matrix and inner membrane proteins. We considered whether the two machineries can function independently of each other in a sequential reaction. Fusion proteins (pF-CCHL) were constructed which contained dual targeting information, one for the intermembrane space present in cytochrome c heme lyase (CCHL) and the other for the matrix space contained in the signal sequence of the precursor of F1-ATPase beta-subunit (pF1 beta). In the absence of a membrane potential, delta psi, the fusion proteins moved into the intermembrane space using the CCHL pathway. In contrast, in the presence of delta psi they followed the pF1 beta pathway and eventually were translocated into the matrix. The fusion protein pF51-CCHL containing 51 amino acids of pF1 beta, once transported into the intermembrane space in the absence of a membrane potential, could be further chased into the matrix upon re-establishing delta psi. The sequential and independent movement of the fusion protein across the two membranes demonstrates that the translocation machineries act as distinct entities. Our results support a model in which the two translocation machineries can function independently of each other, but generally interact in a dynamic fashion to achieve simultaneous translocation across both membranes. In addition, the results provide information about the targeting sequences within CCHL. The protein does not contain a signal for retention in the intermembrane space; rather, it lacks matrix targeting information, and therefore is unable to undergo delta psi-dependent interaction with the protein translocation apparatus in the inner membrane

Functional Characterization of the Eukaryotic Cysteine Desulfurase Nfs1p from Saccharomyces cerevisiae

Previous studies have indicated that the essential protein Nfs1 performs a crucial role in cellular iron-sulfur (Fe/S) protein maturation. The protein is located predominantly in mitochondria, yet low amounts are present in cytosol and nucleus. Here we examined several aspects concerning the molecular function of yeast Nfs1p as a model protein. First, we demonstrated that purified Nfs1p facilitates the in vitro assembly of Fe/S proteins by using cysteine as its specific substrate. Thus, eukaryotic Nfs1 is a functional orthologue of the bacterial cysteine desulfurase IscS. Second, we showed that only the mitochondrial version but not the extramitochondrial version of Nfs1p is functional in generating cytosolic and nuclear Fe/S proteins. Mutation of the nuclear targeting signal of Nfs1p did not affect the maturation of cytosolic and nuclear Fe/S proteins, despite a severe growth defect under this condition. Nfs1p could not assemble an Fe/S cluster on the Isu scaffold proteins when they were located in the yeast cytosol. The lack of function of these central Fe/S cluster assembly components suggests that the maturation of extramitochondrial Fe/S protein does not involve functional copies of the mitochondrial Fe/S cluster assembly machinery in the yeast cytosol. Third, the extramitochondrial version of Nfs1p was shown to play a direct role in the thiomodification of tRNAs. Finally, we identified a highly conserved N-terminal {beta}-sheet of Nfs1p as a functionally essential part of the protein. The implication of these findings for the structural stability of Nfs1p and for its targeting mechanism to mitochondria and cytosol/nucleus will be discussed

Magyarországi eredetű élelmiszerek részesedése a hazai kiskereskedelemben

A kutatás célja az, hogy áttekintést adjunk a magyarországi eredetű élelmiszertermékek piaci részesedéséről a hazai kiskereskedelemben. A Magyarországon tevékenykedő legnagyobb – három hazai és kilenc nemzetközi tulajdonú – kiskereskedelmi lánc egy-egy véletlenszerűen kiválasztott kereskedelmi egységében 2010 októberében lefolytatott, egyszeri állapotfelvételben 10 termékcsoport (húskészítmény, tálcás baromfihús, tálcás sertéshús, tojás, joghurt-kefir-tejföl, sajt-sajtkészítmény-túró, tej, zöldség-gyümölcs – szezonális minta –, méz, lekvár) magyarországi beszállítói részarányát mértük fel. A termékcsoportok kiválasztásánál meghatározó szempont volt, hogy az idetartozó élelmiszerek Magyarországon előállíthatók legyenek. A felmérés eredménye szerint minden vizsgált termékcsoportban 50%-nál nagyobb hazai beszállítói részarány állapítható meg. Egyes termékcsoportoknál – például a tálcás húsoknál, illetve tojásnál – ez az arány 90% feletti. Ugyanakkor a tejtermékek – a folyadéktej kivételével –, valamint a gyümölcsdzsemeknél a hazai eredetű termékek aránya alig haladta meg az 50%-ot. Az összes, általunk vizsgált áruféleségben 76,4% volt a magyarországi termékek aránya. A hazai tulajdonú láncoknál ez az arány magasabb, 82%-os, míg a nemzetközi láncoknál 72,8%-os volt. ------------------------------------------------ The purpose of the study was to estimate the market share of the foodstuffs of Hungarian origin in the retail trade in Hungary. In randomly selected commercial units of the largest 12 retail chains operating in Hungary, out of which 3 were Hungarian-owned and 9 were multinational, a one-shot survey was conducted in October 2010 to assess the share of the Hungarian suppliers regarding 10 food categories (meat products, fresh poultry meat in tray packaging, fresh pork meat in tray packaging, eggs, yogurt–kefir–sour cream, cheese–processed cheese products–cottage-cheese, milk, fruits and vegetables (seasonal sample), honey and jam). A decisive criterion in selecting the food categories was that the foodstuffs could be produced in Hungary as well. The results of the survey show that the market share of the Hungarian suppliers was over 50 percent in every food category examined. In some food categories, e.g. fresh meat in tray packaging and eggs, this proportion was over 90 percent. However, the market share of Hungarian foodstuffs hardly exceeded the 50 percent in the case of milk products, except for milk itself, and in the case of jams. With regard to all food categories the portion of the Hungarian food products was 76.4 percent altogether. In the Hungarian-owned retail-chains this share was larger (82 percent), while the corresponding figure in the multinational stores was 72.8 percent on average

Magyarországi eredetű élelmiszerek részesedése a hazai kiskereskedelemben

A kutatás célja az, hogy áttekintést adjunk a magyarországi eredetű élelmiszertermékek piaci részesedésérÅ‘l a hazai kiskereskedelemben. A Magyarországon tevékenykedÅ‘ legnagyobb – három hazai és kilenc nemzetközi tulajdonú – kiskereskedelmi lánc egy-egy véletlenszerűen kiválasztott kereskedelmi egységében 2010 októberében lefolytatott, egyszeri állapotfelvételben 10 termékcsoport (húskészítmény, tálcás baromfihús, tálcás sertéshús, tojás, joghurt-kefir-tejföl, sajt-sajtkészítmény-túró, tej, zöldség-gyümölcs – szezonális minta –, méz, lekvár) magyarországi beszállítói részarányát mértük fel. A termékcsoportok kiválasztásánál meghatározó szempont volt, hogy az idetartozó élelmiszerek Magyarországon előállíthatók legyenek. A felmérés eredménye szerint minden vizsgált termékcsoportban 50%-nál nagyobb hazai beszállítói részarány állapítható meg. Egyes termékcsoportoknál – például a tálcás húsoknál, illetve tojásnál – ez az arány 90% feletti. Ugyanakkor a tejtermékek – a folyadéktej kivételével –, valamint a gyümölcsdzsemeknél a hazai eredetű termékek aránya alig haladta meg az 50%-ot. Az összes, általunk vizsgált áruféleségben 76,4% volt a magyarországi termékek aránya. A hazai tulajdonú láncoknál ez az arány magasabb, 82%-os, míg a nemzetközi láncoknál 72,8%-os volt. ------------------------------------------------ The purpose of the study was to estimate the market share of the foodstuffs of Hungarian origin in the retail trade in Hungary. In randomly selected commercial units of the largest 12 retail chains operating in Hungary, out of which 3 were Hungarian-owned and 9 were multinational, a one-shot survey was conducted in October 2010 to assess the share of the Hungarian suppliers regarding 10 food categories (meat products, fresh poultry meat in tray packaging, fresh pork meat in tray packaging, eggs, yogurt–kefir–sour cream, cheese–processed cheese products–cottage-cheese, milk, fruits and vegetables (seasonal sample), honey and jam). A decisive criterion in selecting the food categories was that the foodstuffs could be produced in Hungary as well. The results of the survey show that the market share of the Hungarian suppliers was over 50 percent in every food category examined. In some food categories, e.g. fresh meat in tray packaging and eggs, this proportion was over 90 percent. However, the market share of Hungarian foodstuffs hardly exceeded the 50 percent in the case of milk products, except for milk itself, and in the case of jams. With regard to all food categories the portion of the Hungarian food products was 76.4 percent altogether. In the Hungarian-owned retail-chains this share was larger (82 percent), while the corresponding figure in the multinational stores was 72.8 percent on average.magyarországi élelmiszer, piaci részesedés, élelmiszer-kiskereskedelem, Hungarian foods, market share, food trade, Agribusiness, International Relations/Trade, Marketing,

An essential function of the mitochondrial sulfhydryl oxidase Erv1p/ALR in the maturation of cytosolic Fe/S proteins

Biogenesis of Fe/S clusters involves a number of essential mitochondrial proteins. Here, we identify the essential Erv1p of Saccharomyces cerevisia mitochondria as a novel component that is specifically required for the maturation of Fe/S proteins in the cytosol, but not in mitochondria. Furthermore, Erv1p was found to be important for cellular iron homeostasis. The homologous mammalian protein ALR (‘augmenter of liver regeneration’), also termed hepatopoietin, can functionally replace defects in Erv1p and thus represents the mammalian orthologue of yeast Erv1p. Previously, a fragment of ALR was reported to exhibit an activity as an extracellular hepatotrophic growth factor. Both Erv1p and full-length ALR are located in the mitochondrial intermembrane space and represent the first components of this compartment with a role in the biogenesis of cytosolic Fe/S proteins. It is likely that Erv1p/ALR operates downstream of the mitochondrial ABC transporter Atm1p/ABC7/Sta1, which also executes a specific task in this essential biochemical process