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The promoter selectivity factor Sp1 often cooperates with other enhancer-binding proteins to activate transcription. To study the molecular underpinnings of these regulatory events, we have reconstituted in vitro the synergy observed in vivo between Sp1 and the sterol-regulated factor SREBP-1a at the low density lipoprotein receptor (LDLR) promoter. Using a highly purified human transcription system, we found that chromatin, TAFs, and a novel SREBP-binding coactivator activity, which includes CBP, are all required to mediate full synergistic activation by Sp1 and SREBP-1a. The SREBP-binding domain of CBP inhibits activation by SREBP-1a and Sp1 in a dominant-negative fashion that is both chromatin-and activator-specific. Whereas recombinant CBP alone is not sufficient to mediate activation, a human cellular fraction containing CBP can support high levels of chromatin-dependent synergistic activation. Purification of this activity to near homogeneity resulted in the identification of a multiprotein coactivator, including CBP, that selectively binds to the SREBP-1a activation domain and is capable of mediating high levels of synergistic activation by SREBP/Sp1 on chromatin templates. The development of a reconstituted chromatin transcription system has allowed us to isolate a novel coactivator that is recruited by the SREBP-1a activation domain and that functions in concert with TFIID to coordinate the action of multiple activators at complex promoters in the context of chromatin.

Succinate dehydrogenase (EC 1.3.99.1) in the yeast Saccharomyces cerevisiae is a mitochondrial respiratory chain enzyme that utilizes the cofactor, FAD, to catalyze the oxidation of succinate and the reduction of ubiqinone. The succinate dehydrogenase enzyme is a heterotetramer composed of a flavoprotein, an iron-sulfur protein, and two hydrophobic subunits. The FAD is covalently attached to a histidine residue near the amino terminus of the flavoprotein. In this study, we have investigated the attachment of the FAD cofactor with the use of an antiserum that specifically recognizes FAD and hence, can discriminate between apo- and holoflavoproteins. Cofactor attachment, both in vivo and in vitro, occurs within the mitochondrial matrix once the presequence has been cleaved. FAD attachment is stimulated by, but not dependent upon, the presence of the iron-sulfur subunit and citric acid cycle intermediates such as succinate, malate, or fumarate. Furthermore, this modification does not occur with C-terminally truncated flavoprotein subunits that are fully competent for import. Taken together, these data suggest that cofactor addition occurs to an imported protein that has folded sufficiently to recognize both FAD and its substrate.

Introduction Although breastfeeding has been shown to improve health outcomes for infants, African American women initiate and continue breastfeeding at lower rates than women from other racial groups. This scoping review was conducted to assess the effect racism, bias, and discrimination have on breastfeeding care, support, and outcomes for African American women. Methods A scoping review was performed of the literature published between January 2010 through December 2019 using databases MEDLINE via PubMed, CINAHL, Cochrane Library, PsycINFO, and Sociological Abstracts. Studies that examined racism, bias, or discrimination with breastfeeding as an outcome were included. After a review of titles and abstracts of the articles using exclusion and inclusion criteria, 5 full‐text articles were included in the scoping review. Results The qualitative and quantitative studies reviewed provide the perspectives of pregnant and postpartum African American women as well as those of health care providers. African American women's experiences of racism adversely affected both breastfeeding initiation and duration. Health care providers’ biased assumption that African American women would not breastfeed affected the quality of breastfeeding support provided to them. Specifically, African American women received fewer referrals for lactation support and more limited assistance when problems developed. This scoping review provides evidence that African American women experience racism, bias, and discrimination affecting breastfeeding care, support, and outcomes. Discussion Racism, bias, and discrimination are modifiable barriers that adversely affect breastfeeding among African American women. Researchers and health care providers are encouraged to consider the effect of racism, bias, and discrimination on breastfeeding care, support, and outcomes.

Succinate dehydrogenase of the bacterial or inner mitochondrial membrane catalyses the oxidation of succinate to fumarate and directs reducing equivalents into the electron-transport chain. The enzyme is also able to catalyse the reverse reaction, the reduction of fumarate to succinate. The enzyme is composed of four subunits. These subunits include a catalytic dimer composed of a flavoprotein subunit with a covalently bound FAD, and an iron-sulfur protein subunit with three different iron-sulfur centres, which is anchored to the membrane by two smaller integral membrane proteins. The FAD moiety is attached to the flavoprotein subunit by an 8a-[N(3)-histidyl]FAD linkage at a conserved histidine residue, His90 of the Saccharomyces cerevisiae succinate dehydrogenase. By mutating His90 to a serine residue, we have constructed a flavoprotein subunit that is unable to covalently bind FAD. The mutant flavoprotein is targeted to mitochondria, translocated across the mitochondrial membranes, and is assembled with the other subunits where it binds FAD non-covalently. The resulting holoenzyme has no succinate-dehydrogenase activity but retains fumarate reductase activity. The covalent attachment of FAD is therefore necessary for succinate oxidation but is dispensable for both fumarate reduction and for the import and assembly of the flavoprotein subunit.Succinate dehydrogenase (SDH) is a membrane-bound enzyme of the citric acid cycle that catalyses the oxidation of succinate to fumarate. The reducing equivalents are subsequently donated to the electron-transport chain. A closely related enzyme of bacterial membranes is fumarate reductase (FRD). FRD catalyses the reverse reaction, the reduction of fumarate to succinate, allowing cells to grow anaerobically with fumarate as the final electron acceptor. Both SDH and FRD can catalyse succinate oxidation and fumarate reduction but with different efficiencies (Cole et al., 1985 ;Hederstedt and Ohnishi, 1992).SDH and FRD are usually composed of four non-identical subunits : a flavoprotein, an iron-sulfur protein, and two smaller integral membrane proteins. The active site is located in the flavoprotein subunit, which also possesses the covalently bound FAD. The iron-sulfur-protein subunit contains three iron-sulfur clusters : [2Fe-2S], [3Fe-4S], and [4Fe-4S], centres 1, 3, and 2, respectively. The flavoprotein and ironsulfur-protein subunits form a catalytic dimer that is attached to the membrane by the two hydrophobic membrane anchoring proteins that may co-ordinate a b-type heme (except in Escherichia coli FRD) and interact with quinone substrates (Ackrell et al., 1992;Cole et al., 1985). However, voltammeCorrespondence to B. D. Lemire,