Search

Once revealed, a metal cofactor adds new dimensions to understanding protein structure and function; yet, the presence of metal is often unsuspected until the protein is analysed (1,2,5). For example, [...], Metal ion cofactors afford proteins virtually unlimited catalytic potential, enable electron transfer reactions and have a great impact on protein stability (1,2). Consequently, metalloproteins have key roles in most biological processes, including respiration (iron and copper), photosynthesis (manganese) and drug metabolism (iron). Yet, predicting from genome sequence the numbers and types of metal an organism assimilates from its environment or uses in its metalloproteome is currently impossible because metal coordination sites are diverse and poorly recognized (2-4). We present here a robust, metal-based approach to determine all metals an organism assimilates and identify its metalloproteins on a genome-wide scale. This shifts the focus from classical protein-based purification to metal-based identification and purification by liquid chromatography, high-throughput tandem mass spectrometry (HT-MS/MS) and inductively coupled plasma mass spectrometry (ICP-MS) to characterize cytoplasmic metalloproteins from an exemplary microorganism (Pyrococcus furiosus). Of 343 metal peaks in chromatography fractions, 158 did not match any predicted metalloprotein. Unassigned peaks included metals known to be used (cobalt, iron, nickel, tungsten and zinc; 83 peaks) plus metals the organism was not thought to assimilate (lead, manganese, molybdenum, uranium and vanadium; 75 peaks). Purification of eight of 158 unexpected metal peaks yielded four novel nickeland molybdenum-containing proteins, whereas four purified proteins contained sub-stoichiometric amounts of misincorporated lead and uranium. Analyses of two additional microorganisms (Escherichia coli and Sulfolobus solfataricus) revealed species-specific assimilation of yet more unexpected metals. Metalloproteomes are therefore much more extensive and diverse than previously recognized, and promise to provide key insights for cell biology, microbial growth and toxicity mechanisms.

Research describes the purification of the beta-ribofuranosylaminobenzene 5'-phosphate synthase from Methanosarcina thermophila and identification of the enzyme homologs in archaea and in M. extorquens bacterium. The gene encoding the enzyme is overexpressed in Archaeoglobus gulgidus.

Abstract Background Metal-containing proteins comprise a diverse and sizable category within the proteomes of organisms, ranging from proteins that use metals to catalyze reactions to proteins in which metals play key structural roles. Unfortunately, reliably predicting that a protein will contain a specific metal from its amino acid sequence is not currently possible. We recently developed a generally-applicable experimental technique for finding metalloproteins on a genome-wide scale. Applying this metal-directed protein purification approach (ICP-MS and MS/MS based) to the prototypical microbe Pyrococcus furiosus conclusively demonstrated the extent and diversity of the uncharacterized portion of microbial metalloproteomes since a majority of the observed metal peaks could not be assigned to known or predicted metalloproteins. However, even using this technique, it is not technically feasible to purify to homogeneity all metalloproteins in an organism. In order to address these limitations and complement the metal-directed protein purification, we developed a computational infrastructure and statistical methodology to aid in the pursuit and identification of novel metalloproteins. Results We demonstrate that our methodology enables predictions of metal-protein interactions using an experimental data set derived from a chromatography fractionation experiment in which 870 proteins and 10 metals were measured over 2,589 fractions. For each of the 10 metals, cobalt, iron, manganese, molybdenum, nickel, lead, tungsten, uranium, vanadium, and zinc, clusters of proteins frequently occurring in metal peaks (of a specific metal) within the fractionation space were defined. This resulted in predictions that there are from 5 undiscovered vanadium- to 13 undiscovered cobalt-containing proteins in Pyrococcus furiosus. Molybdenum and nickel were chosen for additional assessment producing lists of genes predicted to encode metalloproteins or metalloprotein subunits, 22 for nickel including seven from known nickel-proteins, and 20 for molybdenum including two from known molybdo-proteins. The uncharacterized proteins are prime candidates for metal-based purification or recombinant approaches to validate these predictions. Conclusions We conclude that the largely uncharacterized extent of native metalloproteomes can be revealed through analysis of the co-occurrence of metals and proteins across a fractionation space. This can significantly impact our understanding of metallobiochemistry, disease mechanisms, and metal toxicity, with implications for bioremediation, medicine and other fields.

Describes and evaluates current models of race relations in American society, especially their causal connections. Together these models form a composite of observations and variables that amounts to a heuristic social construction of the American race and ethnic reality. This construction is a more inclusive model to be built upon. (LHW)

Case studies reveal the drift from teenage parenthood to polygamous relationships among young black women who "share" the father of their children with a woman to whom he is legally married. The drift into polygamous relations is described as a forced-choice and explained in terms of the Developmental Task Theory. (PS)

Argues that the Black community should be viewed as a complex of family and kin networks that support the survival and function of the Black family in a racially discriminatory society. Discusses the roles of male and female networks and the Black church. (FMW)

In 1970, there were 85 Black men for every 100 Black women in major American cities. Factors which produced this imbalance in the sex ratio of Blacks include educational, health care, public assistance, and penal correction systems, labor market mechanisms, and the military. (Author/MC)

Living with two parents from birth to age 10 directly delays the age at first pregnancy. A plausible sociological explanation for this path is that two-parent families are able to exercise more qualitative and quantitative control over dating activities, potential sex partners, and social opportunities for sex, such as the parental home. More teenagers who live in two-parent families from birth to age 10 than teenagers who live in one-parent families live in two-parent families after age 10; and living in continuous two-parent households prevents early pregnancy through positive daughter-mother relationships after age 10. A plausible explanation for this path is that during adolescence the daughter-mother relationship is either the most close or the most volatile. Social, emotional, and biological changes are occurring to the daughter during this time. Daughter-mother closeness at this time is conducive to the daughter conforming to the parental expectations about either abstaining from sexual activities altogether or using contraception to avoid early pregnancy. Furthermore, more two-parent families than one-parent families are able to actively control their daughters' contacts, reinforce the value of abstinence, and actually enforce such behavioral standards.

The article presents information on a cross-cultural comparative research of juvenile deviance in two specific cities--one in the United States and the other in Argentina. Data from the juvenile court files at Toledo, Ohio, and Rosario, Argentina, for the years 1966 and 1967 were used. This study used statistical court records, participant observation notes, and published documents. The statistical data from Toledo were taken from the juvenile court reports for the years 1966 and 1967, and from the Model Cities Crime and Delinquency Report published in 1969. Toledo and Rosario are both in the northern temperate zones of their respective countries. Both are inland port cities that handle goods moved internationally by way of the Atlantic Ocean. There are, however, notable differences. Rosario does not have a racial minority as does Toledo with its Afro-American and Mexican populations. Although Toledo is about two-thirds the size of Rosario, it had more juveniles adjudicated by its juvenile agencies during 1966 and 1967. Specifically, Toledo had 2.5 times the adjudicated delinquents that Rosario had.

The limitations of individual therapy in residential institu tions are examined. The data analyzed indicate that delinquent subcultures in residential institutions neutralize and nullify the intended effects of individual therapy. The authors, recognizing the need for a method to supplement individual therapy, present a sociological method for changing the contra-culture to a sup portive culture. [ABSTRACT FROM PUBLISHER]