As organizations strive to expand system capabilities through the development of system-ofsystems (SoS) architectures, they want to know "how much effort" and "how long" to implement the SoS. In order to answer these questions, it is important to first understand the types of activities performed in SoS architecture development and integration and how these vary across different SoS implementat...

Signaling from receptor tyrosine kinases (RTKs)* requires the sequential activation of the small GTPases Ras and Rac. Son of sevenless (Sos-1), a bifunctional guanine nucleotide exchange factor (GEF), activates Ras in vivo and displays Rac-GEF activity in vitro, when engaged in a tricomplex with Eps8 and E3b1-Abi-1, a RTK substrate and an adaptor protein, respectively. A mechanistic understandi...

The bacterial SOS regulon is strongly induced in response to DNA damage from exogenous agents such as UV radiation and nalidixic acid. However, certain mutants with defects in DNA replication, recombination, or repair exhibit a partially constitutive SOS response. These mutants presumably suffer frequent replication fork failure, or perhaps they have difficulty rescuing forks that failed due to...

Son of sevenless (SOS) is a guanine nucleotide exchange factor that regulates cell behavior by activating the small GTPase RAS. Recent in vitro studies have suggested that an interaction between SOS and the GTP-bound active form of RAS generates a positive feedback loop that propagates RAS activation. However, it remains unclear how the multiple domains of SOS contribute to the regulation of th...

The Ras signaling pathway is rapidly activated and then down-regulated following stimulation of multiple cell-surface receptors including the insulin receptor (IR). Much recent attention has focused on elucidating the mechanism of Ras inactivation following IR engagement. Previous data suggest that IR-mediated serine/threonine phosphorylation of the Ras guanine nucleotide exchange factor Sos co...

Genetic and biochemical evidence demonstrated that Eps8 is involved in the routing of signals from Ras to Rac. This is achieved through the formation of a tricomplex consisting of Eps8-E3b1-Sos-1, which is endowed with Rac guanine nucleotide exchange activity. The catalytic subunit of this complex is represented by Sos-1, a bifunctional molecule capable of catalyzing guanine nucleotide exchange...

Many of the DNA damage-inducible genes encoding DNA repair and recombination proteins are expressed as part of the SOS response (39, 40). LexA protein represses the genes of the SOS regulon (Table 1); when DNA damage occurs, RecA protein inactivates the LexA repressor, leading to induction of the SOS response. The SOS response controls the expression of genes involved in recombination repair (d...

The cutting edge in systems development today is in the area of systems of systems, (SoS) large networks of inter-related systems that are developed and managed separately, but that also perform collective activities. Such large systems typically involve constituent systems operating with different life cycles, often with uncoordinated evolution. The result is an ever-changing SoS in which adap...

Background: Biofilms predominate in nearly all nutrient-sufficient ecosystems, both natural and clinical. In clinical settings, bacteria often encounter antimicrobial and DNA damaging agents. Factual evidence shows that more and more biofilm inducing antimicrobials trigger the SOS response of bacteria. This triggering leads to a link between biofilms and SOS. The purpose of this article is to r...

System of Systems (SoS) is a new class of complex software systems resulting from the integration of several independent systems working together. Within a SoS, many participant systems may be integrated and deleted operationally over the time. Each system has an Architecture Model modeled at design time. Thus, the SoS’ software architecture description is represented by an aggregated Architect...