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The Human Microbiome Project (HMP), funded as an initiative of the NIH Roadmap for Biomedical Research (http://nihroadmap.nih.gov), is a multi-component community resource. The goals of the HMP are: (1) to take advantage of new, high-throughput technologies to characterize the human microbiome more fully by studying samples from multiple body sites from each of at least 250 “normal” volunteers; (2) to determine whether there are associations between changes in the microbiome and health/disease by studying several different medical conditions; and (3) to provide both a standardized data resource and new technological approaches to enable such studies to be undertaken broadly in the scientific community. The ethical, legal, and social implications of such research are being systematically studied as well. The ultimate objective of the HMP is to demonstrate that there are opportunities to improve human health through monitoring or manipulation of the human microbiome. The history and implementation of this new program are described here.

(7)(8)(9)(10), the GALl gene (which encodes galactokinase) (7), the ADH2 gene (which encodes alcohol dehydrogenase) (7,11,12), and Ty elements (13,14). These SWI and SNF proteins do not appear to contain any DNA-binding motifs, nor have these proteins exhibited any DNA-binding activity in vitro (7,9,15). SWI2/SNF2, however, contains a domain homologous to certain DNA-dependent ATPases, and a recombinant form of this domain exhibits DNAdependent ATPase activity (16)(17)(18). Genetic data suggest that these SWI and SNF proteins form a complex that is recruited to promoter regions through interactions with gene-specific DNA-binding proteins (7,9,19 Hepes-KOH, pH 7.6/20% glycerol/l mM dithiothreitol/l mM. EDTA/2 ,ug of chymostatin per ml/2 puM pepstatin A/0.6 pM leupeptin/2 mM benzamidine/1 mM phenylmethylsulfonyl fluoride/0.01% Nonidet P-40). The purification was monitored by imiunoblot analysis with antisera to SWI1/ADR6, SWI2/SNF2, and SWI3 proteins.Preparation of Recombinant SNF6 Protein. The SNF6 gene was transferred from the plasmid YCp5O-SNF6 to the Escherichia coli expression vector pETliA (Novagen) and tagged with six histidine residues at its carboxyl terminus by means of a polymerase chain reaction with the oligonucleotide primers BCSNF6N (5'-CCCCAGATCTTACATATGGGT-GTCATCAAGAAGAAA-3') and BCSNF6C (5'-CCCG-GATCCTCTAGACTAGTGATGGTGATGGTGATGTC-CAAAAAATACAGCATCAAGATCTCC-3'). The resulting product was digested with Nde I and BamHI and ligated to complementary sites in pETilA to form pET11A-SNF6HT. BL21 (DE3) cells (Novagen) containing the lysozyme-expressing plasmid pLysS (Novagen) were transformed with pET11A-SNF6HT. The transformant was grown at 300C in LB medium (2 liters) containing 100 pRg of ampicillin per ml and 25 ptg of chloramphenicol per ml to an optical density at 600 nm of 0.7. The culture was induced with 0.5 mM isopropyl P-D-thiogalactoside and grown an additional 2 hr.The cells were harvested by centrifugation at 5000 x g for 10 min, washed with 100 ml of 20 mM Hepes (pH 7.5), and suspended in 100 ml of buffer B (20 mM Hepes, pH 7.5/10% glycerol/5 mM 2-mercaptoethanol/l mM EDTA/2 pg of chymostatin per ml/2 pM pepstatin A/0.6 pM leupeptin/2 mM benzamidine/1 mM phenylmethylsulfonyl fluoride), containing 400 mM NaCl. The suspension was lysed by sonication at 40C and centrifuged at 10,000 x g for 10 min.The pellet, containing the majority of SNF6HT protein, was suspended in 10 ml of buffer-B containing 0.5% Triton X-100 and 1 M lithum chloride, incubated at 40C for 10 min, sonicated briefly, and centrifuged at 10,000 x g for 10 m' at 4°C. The pellet was washed three additional times in the same manner and suspended in 1 ml of buffer B containing 50 mM NaCl and 0.5% SDS. The resulting SNF6HT protein was judged to be roughly 95% pure by SDS/PAGE.Antisera. Approximately 4 mg of purified SNF6HT protein was subjected to electrophoresis in a 10% SDS/polyacrylamide gel. The gel was stained with Coomassie brilliant blue R-250, and a slice containing SNF6HT protein was removed. Rabbits were initially immuni...

Activator proteins bind to enhancer DNA elements and stimulate the initiation of transcription. It has been proposed that activators contact general initiation factors at a promoter, and evidence for such direct interaction has been obtained. Studies of transcription in vitro, however, have suggested that activators might function through an intermediary molecule(s) distinct from the general factors. In the first of these studies, we exploited the finding that one activator could inhibit transcription stimulated by a second activator (activator interference or 'squelching'). This inhibition, which is attributed to competition between the activators for a common target factor, could not be relieved by addition of a large excess of general initiation factors, suggesting that the target for which activators compete is distinct from these factors. Similar conclusions came from the observation that TFIID's expressed from cloned genes fail to replace partially purified 'natural' TFIID fractions in supporting activation, evidently because they lacked some component present in the impure fractions. While these lines of evidence for a novel 'mediator' of activation were negative, we also showed that a partially purified fraction from yeast would reverse activator interference. This positive effect of a presumptive mediator provided an assay for its activity, but its role in activation was still only inferred. We now present direct evidence for a mediator which is required for stimulation of transcription in vitro by the activators GAL4-VP16 and GCN4, but which has no effect on transcription in the absence of activator protein.